cloud backup and recovery · 2020. 6. 14. · the backups generated by the original backup policy...

Cloud Backup and Recovery

FAQs

Issue 02

Date 2020-04-08

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2020. All rights reserved.

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Issue 02 (2020-04-08) Copyright © Huawei Technologies Co., Ltd. i

Contents

1 About Concepts........................................................................................................................ 11.1 What Are Full Backup and Incremental Backup?.........................................................................................................11.2 What Are the Differences Between Backup and Disaster Recovery?....................................................................11.3 What Are the Differences Between Backups and Snapshots?.................................................................................21.4 Why Is the Backup Size Greater Than the Actual Disk Capacity?.......................................................................... 31.5 What Are the Differences Between Backups and Images?.......................................................................................41.6 What Are the Differences Between Cloud Server Backup and Cloud Disk Backup?........................................61.7 Why Does the Used Capacity of a Vault Change Slightly After I Deleted Unwanted Backups?................. 6

2 About Billing............................................................................................................................. 82.1 How Is CBR Billed?.................................................................................................................................................................. 82.2 How Large of a Vault Do I Need?..................................................................................................................................... 92.3 What Is the Billing Cycle and Pay Time of the Pay-per-Use Mode?......................................................................92.4 How Do I Disable CBR?.......................................................................................................................................................102.5 How Do I Unsubscribe from CSBS or VBS Resource Packages?........................................................................... 102.6 Can I Change a Server Backup Vault to a Disk Backup Vault or the Other Way Around?.........................122.7 What Charges Will I Incur When Using a Backup to Create an Image?........................................................... 12

3 About Backup......................................................................................................................... 133.1 Do I Need to Stop the Server Before Performing a Backup?.................................................................................133.2 Can I Back Up a Server Deployed with Databases?..................................................................................................133.3 How Can I Distinguish Automatic Backups From Manual Backups?..................................................................143.4 Can I Choose to Back Up Only Some Partitions of a Disk?....................................................................................143.5 Does CBR Support Cross-Region Backup?.................................................................................................................... 143.6 Can I Back Up Two Disks to One Target Disk?........................................................................................................... 143.7 How Do I Replicate a Disk to the Same AZ in a Region as the Source Disk?................................................. 143.8 Can I Migrate Backups Between Vaults?...................................................................................................................... 153.9 Will the Server Performance Be Affected If I Delete Its Backups?.......................................................................153.10 Can I Use Its Backup for Restoration After a Resource Is Deleted?..................................................................153.11 How Many Backups Can I Create for a Resource?..................................................................................................153.12 Can I Use an Incremental Backup to Restore Data After a Full Backup Is Deleted?..................................153.13 Can I Stop an Ongoing Backup Task?......................................................................................................................... 153.14 How Do I Reduce the Vault Space Occupied by Backups?.................................................................................. 163.15 How Do I View the Size of Each Backup?.................................................................................................................. 20

Cloud Backup and RecoveryFAQs Contents

Issue 02 (2020-04-08) Copyright © Huawei Technologies Co., Ltd. ii

4 About Restoration................................................................................................................. 224.1 Do I Need to Stop the Server Before Restoring Data Using Backups?...............................................................224.2 Can I Use a System Disk Backup to Recover an ECS?.............................................................................................. 224.3 Do I Need to Stop the Server Before Restoring Data Using Disk Backups?.....................................................224.4 Can a Server Be Restored Using Its Backups After It Is Changed?...................................................................... 224.5 Can a Disk Be Restored Using Its Backups After Its Capacity Is Expanded?.................................................... 234.6 What Can I Do if the Password Becomes a Random One After I Use a Backup to Restore a Server orUse an Image to Create a Server?......................................................................................................................................... 234.7 What Changes Will Be Made to the Original Backup When I Use the Backup to Restore a Server?..... 234.8 How Do I Restore Data on the Original Server to a New Server?.......................................................................244.9 How Do I Restore a Data Disk Backup to a System Disk?..................................................................................... 24

5 Policies..................................................................................................................................... 255.1 How Do I Configure Automatic Backup for a Server or Disk?.............................................................................. 255.2 Why Does the Retention Rule Not Take Effect After Being Modified?.............................................................. 255.3 How Do I Back Up Multiple Resources at a Time?................................................................................................... 27

6 Others...................................................................................................................................... 286.1 Is There a Quota for CBR Vaults?....................................................................................................................................286.2 What Can I Do If the Vault Capacity Is Insufficient?................................................................................................ 286.3 Will Backup Continue If the Usage of a Vault Reaches the Upper Limit?........................................................286.4 Can I Export Disk Backup Data to Another Server?..................................................................................................286.5 Can I Download Backup Data to a Local PC?............................................................................................................. 296.6 How Do I Copy Disk Data to Another Account?........................................................................................................ 296.7 What Should I Do If I Receive an Email or SMS Message Indicating a Backup Failure?............................. 29

Cloud Backup and RecoveryFAQs Contents

Issue 02 (2020-04-08) Copyright © Huawei Technologies Co., Ltd. iii

1 About Concepts

1.1 What Are Full Backup and Incremental Backup?After an initial full backup, a server continues to be backed up incrementally bydefault.

● The initial full backup covers only the used capacity of a disk. If a 100 GB diskcontains 40 GB data, the initial backup consumes 40 GB backup space.

● Subsequent incremental backup backs up data changed since the last backup.If 5 GB data changed since the last backup, only the 5 GB changed data willbe backed up.

CBR allows you to use any backup, no matter it is a full or incremental one, torestore the full data of a resource. By virtue of this, manual or automatic deletionof a backup will not affect the restoration function.

Suppose server X has backups A, B, and C (in time sequence) and every backupinvolves data changes. If backup B is deleted, you can still use backup A or C torestore data.

NO TE

In extreme cases, the size of a backup is the same as the disk size. The used capacity in afull backup and the changed capacity in an incremental backup are calculated based on thedata block change in a disk, not by calculating the file change in the operating system. Thesize of a full backup cannot be evaluated based on the file capacity in the operatingsystem, and the size of an incremental backup cannot be evaluated based on the file sizechange.

1.2 What Are the Differences Between Backup andDisaster Recovery?

The following table lists the main differences between backup and disasterrecovery (DR).

Cloud Backup and RecoveryFAQs 1 About Concepts

Issue 02 (2020-04-08) Copyright © Huawei Technologies Co., Ltd. 1

Table 1-1 Differences between backup and DR

Item Backup DR

Purpose To prevent data loss. Itadopts the snapshot orbackup techniques togenerate data backups thatcan be used to restore datawhen data loss orcorruption occurs.

To ensure service continuity. It takesthe replication techniques (such asapplication-layer replication, host-based replication at the I/O layer,and storage-layer replication) toconstruct standby service hosts anddata in a remote center, so that theremote center can take over serviceswhenever the primary center isfaulty.

Scenario It offers protection againstvirus attacks, accidentaldeletions, software andhardware faults.

It enables failover upon softwareand hardware faults, as well asnatural disasters, such as tsunami,fires, and earthquakes, to fastrecover services. When the source AZrecovers, you can easily fail back tothe source AZ.

Cost The cost is 1 to 2% of theproduction system's.

The cost is 20 to 100% of theproduction system's, varying withthe RPO/RTO requirements. Foractive-active DR, the service systemdeployed in the standby center isrequired to be the same as that inthe active system. In this case, thecost on infrastructure doubles.

NO TE

RPO is the abbreviation of Recovery Point Objective and specifies the maximum acceptableperiod in which data might be lost.RTO is the abbreviation of Recovery Time Objective and specifies the maximum acceptableamount of time for restoring the entire system after a disaster happens.

1.3 What Are the Differences Between Backups andSnapshots?

Both backups and snapshots provide data redundancy for disks to improve datareliability. Table 1-2 lists the differences between them.



Table 1-2 Differences between backups and snapshots

Item StorageSolution

DataSynchronization

DR Range ServiceRecovery

Backup Backup data isstored in OBS,instead of disks.This ensuresdata restorationupon disk dataloss orcorruption.

A backup isthe data copyof a disk at agiven point intime. CBRsupportsautomaticbackup byconfiguringbackuppolicies.Deleting adisk will notclear itsbackups.

A backup andits source diskreside in thesame AZ.

Data can berecovered andservices canbe restored byrestoring thebackup datato originaldisks orcreating newdisks frombackups,ensuringexcellent datareliability.

Snapshot Snapshot datais stored withdisk data.NOTE

Creating abackup requiresa certainamount of timebecause dataneeds to betransferred.Therefore,creating orrolling back asnapshotconsumes lesstime thancreating abackup.

A snapshot isthe state of adisk at aspecific pointin time. Whenyou deletethe disk, thesnapshots ofthe disk arealso deleted.

A snapshotand its sourcedisk reside inthe same AZ.

You can use asnapshot toroll back itsoriginal diskor create adisk for datarestorationand servicerecovery.

1.4 Why Is the Backup Size Greater Than the ActualDisk Capacity?

Symptoms● Files are stored and backed up on a server. After a file is added or deleted, the

size of the original backup does not change.● The ECS backup size is larger than the used disk space displayed in the file

system.



Possible CausesThe possible causes are as follows:

● The metadata of the file systems in the disk occupies disk space.● The disk is formatted. For example, after the Windows operating system is

formatted, if writes have been performed to all data on the disk, then theentire disk needs to be backed up. In this case, the backup softwarecompresses all-zero data.

● The backup software monitors the I/O writes to determine which data ischanged and needs to be backed up. After a file is deleted from the filesystem, the file is recorded as changed data and will be backed up.

1.5 What Are the Differences Between Backups andImages?

CBR and Image Management Service (IMS) have some complementary functionsand can be used together in certain scenarios. Like CBR, IMS can also be used toback up ECSs.

Differences Between Backups and ImagesTable 1-3 lists the differences between them.

Table 1-3 Differences between backups and images

Item CBR IMS

Concept A backup contains the status,configuration, and data of acloud server or disk stored ata specific time point forrecovery in case of a fault. It isused to ensure data securityand improve availability.

An image provides allinformation required for startinga cloud server. It is used tocreate a cloud server and deploysoftware environments inbatches. A system disk imagecontains an OS and pre-installedapplication software for runningservices. A data disk imagecontains service data. A full-ECSimage contains both a systemdisk image and data diskimages.



Item CBR IMS

Usagemethod

● Data storage location:Unlike server or disk data,backups are stored in OBS.Deleting a disk will notclear its backups.

● Operation object: A serveror disk can be backed up ata given point in time. CBRsupports automatic backupand automatic deletion byconfiguring backup policies.

● Usage: Backups can beused to restore data to theoriginal server or disk, or tocreate a new disk or full-ECS image.

● Support exporting to alocal PC: No

● Data storage location: Unlikeserver or disk data, backupsare stored in OBS. If a serveror disk that is created usingan image is deleted, theimage will not be cleared.

● Operation object: The systemdisk and data disks of aserver can be used to createprivate images. You can alsocreate private images usingexternal image files.

● Usage: System disk images orfull-ECS images can be usedto create new servers, anddata disk images can be usedto create new disks for servicemigration.

● Support exporting to a localPC: Yes However, full-ECSimages cannot be exported toa local PC.

Applicationscenarios

CBR applies to the followingscenarios:● Data backup and

restoration● Rapid service deployment

and migration

IMS applies to the followingscenarios:● Server migration to the cloud

or between clouds● Deploying a specific software

environment● Deploying software

environments in batches● Backing up server operating

environments

Advantages Supports automatic backup.Data on a server or disk at acertain time point can beretained periodically orquantitatively. You can backup on-premises VMware VMs,synchronize the backups tothe cloud, and then use thebackups to restore data tonew ECSs.

Supports system disk backup.You can import the data diskimage of a local server or aserver provided by another cloudplatform to IMS and then usethe image to create an EVS disk.



NO TE

Although backups and images are stored in OBS, you cannot view backup and image datain OBS, because they do not occupy your resources. Backup fees are charged according toCBR's billing standard, and image storage fees are charged according to OBS's billingstandard.

Relationship Between Backups and Images1. You can use an ECS backup to create a full-ECS image.2. Before creating a full-ECS image for an ECS, you need to back up the target

ECS.3. A backup is compressed when it is used to create an image. Therefore, the

size of the generated image is smaller than that of the backup.

1.6 What Are the Differences Between Cloud ServerBackup and Cloud Disk Backup?

Table 1-4 describes the differences between cloud server backup and cloud diskbackup.

Table 1-4 Differences between cloud server backup and cloud disk backup

Item Cloud Server Backup Cloud Disk Backup

Backup orrestorationobjects

All disks (system and datadisks) on a server

One or more specified disks(system or data disks)

Recommendedscenario

An entire cloud server needsto be protected.

Only data disks need to bebacked up, because the systemdisk does not contain personaldata.

Advantages All disks on a server arebacked up at the same time,ensuring data consistency.

Backup cost is reduced withoutcompromising data security.

1.7 Why Does the Used Capacity of a Vault ChangeSlightly After I Deleted Unwanted Backups?

SymptomsAfter unwanted backups are deleted from the vault, the used capacity of the vaultdecreases by only 1 GB to 2 GB.

Possible CausesThe backup mechanism of CBR:



● By default, CBR performs a full backup for a resource for the first time andbacks up all used data blocks. All subsequent backups are incremental. Anincremental backup backs up only the data blocks changed since the lastbackup.

● Each incremental backup is a virtual full backup. Correlated data blocks areindexed by using pointers.

● When you delete a backup, no matter manually or automatically, only datablocks that are not referenced by other backups will be deleted.

Figure 1-1 Backup mechanism



2 About Billing

2.1 How Is CBR Billed?CBR's billing items include the storage space and data traffic. The storage fee isbilled based on the type of the vaults. The billing items are detailed as follows:

Storage space:

● Disk backup vault that needs to be purchased before backing up EVS disks● Server backup vault that needs to be purchased before backing up common

cloud servers● File system backup vault that needs to be purchased before backing up SFS

Turbo file systems● Application-consistent backup vault that needs to be purchased before

backing up cloud servers deployed with databases● Hybrid cloud backup vault that needs to be purchased before backing up

VMware VMs and OceanStor Dorado storage systems in on-premises datacenters

Data traffic:

Outbound data traffic over the Internet: for hybrid cloud backup

Case 1:

Pay-per-use vault for cloud servers without databases deployed:

A user has a 100 GB cloud server and a 400 GB cloud server backup vaultpurchased in the CN North-Beijing1 region, and the cloud server is associated withthe vault. Then the user is billed for the 400 GB cloud server backup vault.

Case 2:

Pay-per-use vault for cloud servers with databases deployed:

A user has a 100 GB cloud server deployed with databases and an 800 GBapplication-consistent backup vault purchased in the CN North-Beijing1 region,and the cloud server is associated with the vault. Then the user is billed for the800 GB application-consistent backup vault.

Cloud Backup and RecoveryFAQs 2 About Billing


Case 3:

Replicating a backup to another region in pay-per-use mode:

A user purchases a 100 GB cloud server backup vault A in the CN North-Beijing4region, and the backup data occupies 40 GB storage space. The user alsopurchases a 200 GB replication vault B in the CN South-Guangzhou region andreplicates data in vault A to vault B, without using the acceleration service. In thiscase, the user is billed for the 100 GB and 200 GB vault, as well as the 40 GBcross-region replication data traffic.

For detailed prices, see the CBR pricing details.

2.2 How Large of a Vault Do I Need?

Manual Backup Scenario

If only manual backup is required, you are advised to set the vault capacity to atleast twice the total capacity of the resources you want to back up.

Automatic Backup Scenario

If automatic backup is required, use the following formula to estimate therequired capacity of the vault to be created:

Vault capacity (GB) = [Initial disk usage (GB) + Backup retention period (days)/Backup cycle (days) x Daily data volume changes (GB)] x 120%

NO TE

If you set that backups are retained based on backup quantity, you can calculate the vaultcapacity you need by converting the number of retained backups to backup retentionperiod. For example, if a company backs up data once a day and the number of retainedbackups is set to 7, then the retention period can be deemed as 7 days.

Vault cannot be scaled down. You are advised to adjust the value based on youractual needs after the calculation.

Example

Financial company A has an 800 GB cloud server and has used 500 GB of it. Thedaily data change volume is about 10 GB. As scheduled, the company's data isbacked up twice at 02:00 and 20:00 every day, and backups are retained for onemonth. The capacity of a server backup vault required by the company can beestimated using the following formula:

Required vault capacity = [(500+30/(1/2) x 10] x 120% = 1320 GB

2.3 What Is the Billing Cycle and Pay Time of the Pay-per-Use Mode?

The vaults are billed hourly and are paid after usage.



https://www.huaweicloud.com/intl/en-us/pricing/index.html?tab=detail#/cbr

2.4 How Do I Disable CBR?If you enabled CBR when purchasing an ECS but want to disable it afterward, goto CBR Console and then delete all vaults on the cloud server backup, cloud diskbackup, file system backup, and hybrid cloud backup pages. See Figure 2-1.

● If a message is displayed indicating that the ECS backup cannot be deleted,check whether the backup has been used to create an image and whether theimage has been deleted.

● If you have not migrated resources to CBR yet, switch back to the CSBS or VBSconsole page to delete the backups.

● To delete CSBS backups displayed on the VBS console page, go to theBackups tab page on CSBS Console.

Figure 2-1 Deleting vaults

2.5 How Do I Unsubscribe from CSBS or VBS ResourcePackages?

If you want to migrate resources from CSBS and VBS to CBR, the original yearly/monthly CSBS and VBS packages cannot be migrated. In this case, you canunsubscribe from the packages yourself or submit a service ticket. For detailsabout the unsubscription rules, see Unsubscription Rules.

Unsubscribing from a Resource Package By Self Service

Step 1 Log in to CSBS Console.

Step 2 Click Billing in the upper right corner of the page to go to the Billing Center.

Step 3 In the left navigation pane, choose Unsubscriptions and Changes >Unsubscriptions. The resources you purchased are displayed.

Step 4 Select an unwanted resource package and click Unsubscribe. See Figure 2-2.



https://console-intl.huaweicloud.com/ticket/?locale=en-us#/ticketindex/createIndex

https://support.huaweicloud.com/intl/en-us/usermanual-billing/en-us_topic_0083138805.html

Figure 2-2 Unsubscribing from a resource package

----End

Unsubscribing from a Resource Package By Submitting a Service Ticket

Step 1 Log in to the management console.

Step 2 In the upper right corner of the page, choose Service Tickets > Create ServiceTicket. The Create Service Ticket page is displayed. Click Subscriptions on theSelect Ticket Type tab page.

Figure 2-3 Going to the Subscriptions page

Step 3 On the Select Subtype tab page, choose Unsubscription - UnsubscriptionProblem > Create Service Ticket.



Figure 2-4 Creating a service ticket

Step 4 Enter a description, for example, "unsubscribing from CSBS/VBS resourcepackages", in the text box next to Problem Description and set other parametersas required. Then click Submit.

----End

2.6 Can I Change a Server Backup Vault to a DiskBackup Vault or the Other Way Around?

No. You can unsubscribe from or delete unwanted vaults and then purchase a newone. For details about the unsubscription rules, see Unsubscription Rules.

2.7 What Charges Will I Incur When Using a Backup toCreate an Image?

You will be charged only for the backup vault capacity when you use a cloudserver backup to create an image.

For detailed prices, see the CBR pricing details.



https://support.huaweicloud.com/intl/en-us/usermanual-billing/en-us_topic_0083138805.html

https://www.huaweicloud.com/intl/en-us/pricing/index.html?tab=detail#/cbr

3 About Backup

3.1 Do I Need to Stop the Server Before Performing aBackup?

No. You can back up servers that are in use. When a server is running, data iswritten onto disks on the server, and some newly generated data is stored in theserver memory as cached data. During a backup task, the data in the memory willnot be automatically written onto disks, resulting in data inconsistency betweendisks and their backups.

To ensure data integrity, back up the server during off-peak hours when no writeoperation is performed on the disks. For applications that require strictconsistency, such as databases and email systems, you are advised to enable theapplication-consistent backup function.

3.2 Can I Back Up a Server Deployed with Databases?Yes. CBR provides the application-consistent backup function. For details about thefunction compatibility, see Table 3-1. For applications or databases with which theapplication-consistent function is incompatible, you are advised to suspend alldata write operations before performing backup. If write operations cannot besuspended, you can stop the application systems or the server for offline backup. Ifyou do not perform the preceding operations before backup, status of the serverafter restoration will be similar to restart upon an unexpected power failure. Inthis case, log rollback will be performed on databases to keep data consistent.

Table 3-1 OSs that support installation of the Agent

Database OS Version

SQL Server2008/2012

Windows Windows Server 2008, 2008 R2, 2012, and 2012 R2for x86_64

Cloud Backup and RecoveryFAQs 3 About Backup


Database OS Version

SQLServer2014/2016/EE

Windows Windows Server 2012, 2012 R2, and 2016Datacenter for x86_64

MySQL5.5/5.6/5.7

Red Hat Red Hat Enterprise Linux 6 and 7 for x86_64

SUSE SUSE Linux Enterprise Server 11 and 12 for x86_64

CentOS CentOS 6 and 7 for x86_64

EulerOS EulerOS 2.2 and 2.3 for x86_64

HANA1.0/2.0

SUSE SUSE Linux Enterprise Server 12 for x86_64

3.3 How Can I Distinguish Automatic Backups FromManual Backups?

They can be distinguished by name prefix:

● Automatic backups: autobk_xxxx● Manual backups: manualbk_xxxx or customized names

3.4 Can I Choose to Back Up Only Some Partitions of aDisk?

No. The minimum backup granularity supported by CBR is disks.

3.5 Does CBR Support Cross-Region Backup?No. CBR supports only backup and restoration within a region but not acrossregions.

3.6 Can I Back Up Two Disks to One Target Disk?No. One target disk corresponds to one source disk. The data of two disks cannotbe backed up to one target disk.

3.7 How Do I Replicate a Disk to the Same AZ in aRegion as the Source Disk?

Back up the desired disk. Then use the disk backup to create a new disk, andselect the same AZ as that of the source disk for the new one.



3.8 Can I Migrate Backups Between Vaults?No, backups cannot be migrated between vaults. Therefore, properly plan thestorage usage of vaults before backup.

3.9 Will the Server Performance Be Affected If I DeleteIts Backups?

No. Backups are not stored on a server. Therefore, deleting its backups has noimpact on the server performance.

3.10 Can I Use Its Backup for Restoration After aResource Is Deleted?

Yes. Resources and backups are not stored together. If a resource is deleted, itsbackup still stays in your CBR vault. You can use the backup to restore theresource to a backup point in time.

3.11 How Many Backups Can I Create for a Resource?You can create as many backups for a resource as needed.

3.12 Can I Use an Incremental Backup to Restore DataAfter a Full Backup Is Deleted?

CBR allows you to use any backup, no matter it is a full or incremental one, torestore the full data of a resource. By virtue of this, manual or automatic deletionof a backup will not affect the restoration function.

Suppose server X has backups A, B, and C (in time sequence) and every backupinvolves data changes. If backup B is deleted, you can still use backup A or C torestore data.

3.13 Can I Stop an Ongoing Backup Task?No. An ongoing backup task cannot be stopped.



3.14 How Do I Reduce the Vault Space Occupied byBackups?

Symptom

The size of a disk backup is much greater than the used space of the diskdisplayed on a server. Even if you delete large files from the disk and back up thedisks again, the backup size does not reduce significantly.

Possible Causes

After files are deleted from a disk, the data remains though it is no longeravailable. When you use CBR to back up a disk, all data, including those invisibledata, on the disk, will be backed up.

Solutions

You can zero out the remaining free disk space to completely erase unnecessarydisk space, thereby reducing the vault space occupied by backups.

NO TICE

Note: Zeroing out a disk's remaining space does not affect the data in the usedspace. After a zero-out, the deleted data cannot be recovered. This operation mayaffect disk I/Os. Therefore, zero out a disk during off-peak hours.

Wiping Out a Disk's Free Space in Windows

We will be using Windows 2016 as an example to illustrate how to zero out adisk's remaining free space. This operation is dangerous and may cause data loss.You are advised to back up data in advance.

Step 1 Log in to CBR Console and click the target vault to view its basic information. Youcan see that the example vault has only one backup. See Figure 3-1.

Figure 3-1 Confirming the backup size



Step 2 Log in to the server and right-click to view the disk attributes. See Figure 3-2.

The used disk space is only 25.1 GB, but the backup size is 28 GB.

Figure 3-2 Checking the used server space

Step 3 Run the following command in the CLI. In the command, C indicates the driveletter of the partition and can be changed as needed.

cipher /w:C

Step 4 After the disk is erased with 0x00, hold on Ctrl and C to stop the subsequentwrites. In this way, the remaining space is filled with zeros. See Figure 3-3.

If this program is complete, the remaining disk space will be filled with randomdata, data will be written to the entire disk, and the backup size will be larger.

Figure 3-3 Stopping subsequent writes

Step 5 Log in to CBR Console and delete the original backup. Back up the server again.After the backup is complete, check the space occupied by the backup. See Figure3-4. You can now see that the backup size is greatly reduced.

Figure 3-4 Confirming the disk backup size after the zero-out



NO TE

In addition to the cipher tool mentioned in this document, you can also use a third-partytool (the security needs to be determined by yourself) to fill the free space with 0.

----End

Wiping Out a Disk's Free Space in Linux

This operation is dangerous and may cause data loss. You are advised to back updata in advance.

Step 1 Log in to CBR Console and click the target vault to view its basic information. Youcan see that the example vault has only one backup. See Figure 3-5.

Figure 3-5 Confirming the backup size

Step 2 Log in to the server and run the df -hT command to check the disk usage. SeeFigure 3-6.

You can see that the used disk space is only 1.4 GB, but the backup size is 8 GB.

Figure 3-6 Checking the used server space

Step 3 Use the dd command to fill the disk with zeros. Note: The dd command isdangerous. You are advised to back up data before running the command. Fordetails about the parameters, see Table 3-2.

dd if=/dev/zero of=/tmp/file0 bs=1G count=36



Table 3-2 Parameter description

Parameter Description

if=[Input filename]

Enter the input file name. The default value is standardinput. /dev/zero is an input device that you can use toinitialize files. The device provides as many zeros as you want.It can be used to write string 0 to a device or file.

of=[Output filename]

Enter the output file name. The default value is standardoutput. In this example, file /tmp/file0 is the output file.

bs=[bytes] bs=[bytes] defines the size of the input and output blocks. Inthis example, the value is 1 GB.

count=[blocks] count=[blocks] sets the number of blocks copied. The blocksize is specified by bs. In this example, the value is 36.

NO TE

The newly created file0 also occupies the disk space (which will be deleted in Step 4). Inthis example, the remaining disk space is 37 GB. Obviously, the size of file0 (1 GB x 36) issmaller than 37 GB, which ensures the normal running of the system. Set commandparameter values based on site requirements.

Figure 3-7 shows the command running procedure. The time required forcompleting the writing depends on the disk available space.

Figure 3-7 Running the dd command

After the writing is complete, run the df -hT command to check the disk status.See Figure 3-8.

Figure 3-8 Zero-out complete

Step 4 Run the rm /tmp/file0 command to delete file0. See Figure 3-9.



Figure 3-9 Deleting the file0

Step 5 Run the df -hT command to check the disk space usage. See Figure 3-10.

Figure 3-10 Confirming the used space of the server again

Step 6 Log in to CBR Console and delete the original backup. Back up the server again.After the backup is complete, check the space occupied by the backup. See Figure3-11. You can now see that the backup size is greatly reduced.

Figure 3-11 Checking the backup size after the zero-out

----End

3.15 How Do I View the Size of Each Backup?You cannot view the size of each backup.

However, you can view the size of all backups for each resource. On the Backupstab page, click the name of the target backup to view its details. See Figure 3-12.



Figure 3-12 Checking the size of all backups of a server



4 About Restoration

4.1 Do I Need to Stop the Server Before Restoring DataUsing Backups?

The system shuts down the server before restoring server data, and automaticallystarts up the server after the restoration is complete.

If you deselect Start the server immediately after restoration, you need tomanually start the server after the restoration is complete.

4.2 Can I Use a System Disk Backup to Recover an ECS?Yes. However, before the recovery, you need to detach the system disk to berecovered from the ECS.

You can also use a backup of the system disk to create new disks. However, newlycreated disks cannot be used as system disks.

4.3 Do I Need to Stop the Server Before Restoring DataUsing Disk Backups?

Yes. Before restoring the disk data using a disk backup, you must stop the serverto which the disk is attached, and detach the disk from the server. After the diskdata is restored, attach the disk to the server and start the server.

4.4 Can a Server Be Restored Using Its Backups After ItIs Changed?

Yes. If a server has been backed up and changed such as adding, deleting, orexpanding disks, its backups can still be used to restore data. You are advised toback up data again after the change.

Cloud Backup and RecoveryFAQs 4 About Restoration


If you have added a disk after backup, using the backup to restore data will notchange the data on the newly added disk.

If you have deleted a disk after backup, data restoration using the backup will notinclude the deleted disk.

4.5 Can a Disk Be Restored Using Its Backups After ItsCapacity Is Expanded?

Yes. After restoration, the capacity of the expanded disk goes back to the originalcapacity before expansion. If you want to use the capacity added to the disk, youneed to attach the restored disk to a server, log in to the server, and thenmanually modify the file system configuration. For detailed operations, seesections about post-expansion operations on disks in the Elastic Volume ServiceUser Guide.

4.6 What Can I Do if the Password Becomes a RandomOne After I Use a Backup to Restore a Server or Use anImage to Create a Server?

For details about how to reset the password, see Resetting the Password forLogging In to an ECS in the Elastic Cloud Server User Guide.

4.7 What Changes Will Be Made to the OriginalBackup When I Use the Backup to Restore a Server?

● For Linux:– Check whether drivers related to the PV driver exist. If yes, delete them.– Modify the grub and syslinux configuration files to add the OS kernel

boot parameters and change the disk partition name to UUID=UUID ofthe disk partition.

– Change the names of the disk partitions in the /etc/fstab file toUUID=UUID of the disk partition.

– Delete services of VMware tools.– Linux OSs automatically copy the built-in VirtIO driver to initrd or

initramfs.● For Windows:

– Inject the VirtIO driver offline to solve the problem that the systemcannot start when UVP VMTools is not installed.



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4.8 How Do I Restore Data on the Original Server to aNew Server?

To restore backup data to a new server, you can create an image using a serverbackup and then use the image to create a new server. For details, see Using aBackup to Create an Image.

If a new server has already been created, you can back up the disks, create newones using the backups, and then attach the new disks to the new server. In thiscase, however, data consistency may not be ensured.

4.9 How Do I Restore a Data Disk Backup to a SystemDisk?

You can use a disk backup to create a new disk following instructions in Using aBackup to Create a Disk and attach the new disk to a server followinginstructions in Attaching a Non-Shared Disk. Then copy data in the data disk tothe system disk.



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5 Policies

5.1 How Do I Configure Automatic Backup for a Serveror Disk?

1. Log in to CBR Console and click Cloud Server Backup or Cloud Disk Backupon the left navigation pane. On the displayed page, create a backup vault. Itis recommended that the capacity of the vault be at least twice the total sizeof resources to be backed up.

2. Associate resources with the vault during or after the purchase.3. After the resources are associated, go to the Policies page to configure a

backup policy. You are advised to back up data during off-peak hours, forexample, early in the morning. Set the backup retention rule as needed. If thevault capacity is small, you are advised to reduce the number of backups thatcan be retained and the retention period. Retention rule does not apply tomanual backups.

4. Apply the policy you defined to the vault. The system then will back up theresources that are associated with the vault at the specified time and retainsthe backups based on the retention rule.

5.2 Why Does the Retention Rule Not Take Effect AfterBeing Modified?

A retention rule does not take effect immediately after being modified in thefollowing scenarios:

The Retention Rule Remains to Be by Backup Quantity, With Only theConfigured Quantity Changed

The new retention rule does not take effect on the backups generated by theoriginal backup policy, but only on the new backups. The backups generated bythe original backup policy still follow the original retention rule.

For example: At 10:00 a.m. on Monday, a user sets the backup execution time ofpolicy A to 02:00 a.m. every day, sets the rule to retaining three backups, and

Cloud Backup and RecoveryFAQs 5 Policies


associates a disk. At 10:00 a.m. on Thursday, three backups are retained. Then theuser modifies the retention rule to retaining one backup. However, this newretention rule does not take effect immediately. Instead, it retains only thegenerated backup at 02:00 a.m. on Friday. At then, the three backups generatedby the original policy have been deleted.

The Retention Rule Is Changed From by Backup Quantity to by RetentionPeriod or Permanent

The new retention rule does not take effect on the backups generated by theoriginal backup policy. The backups generated by the original backup policy willnot be automatically deleted.

For example: At 10:00 a.m. on Monday, a user sets the backup execution time ofpolicy A to 02:00 a.m. every day, sets the rule to retaining three backups, andassociates a disk. At 10:00 a.m. on Thursday, three backups are retained. Then theuser modifies the retention rule to deleting the backup generated one month ago.At 02:00 a.m. on Friday, the backup generated by the new backup policy isretained and the three backups generated by the original policy still exist.

The Retention Rule Is Changed From by Retention Period to By a NewRetention Period or Permanent

The new retention rule does not take effect on the backups generated by theoriginal backup policy, but only on the new backups. The backups generated bythe original backup policy still follow the original retention rule.

For example: At 10:00 a.m. on August 5, a user sets the backup execution time ofpolicy A to 02:00 a.m. every day, sets the retention rule to deleting the backupgenerated one month ago, and associates a disk. At 10:00 a.m. on August 8, threebackups are retained. Then the user modifies the retention rule to deleting thebackup generated three months ago. At 02:00 on September 6, the backupgenerated by the original backup policy on August 6 is deleted, and the backupgenerated on August 9 will be deleted two months later.

The Retention Rule Is Changed From by Retention Period to by QuantityThe new retention rule does not take effect on the backups generated by theoriginal backup policy, but only on the new backups. The backups generated bythe original backup policy still follow the original retention rule.

For example: At 10:00 a.m. on August 5, a user sets the backup execution time ofpolicy A to 02:00 a.m. every day, sets the retention rule to deleting the backupgenerated one month ago, and associates a disk. At 10:00 a.m. on August 8, threebackups are retained. Then the user modifies the retention rule to retaining onebackup. At 10:00 on August 10, the backup generated on August 9 has beendeleted and the backup generated on August 10 is retained. However, the backupsgenerated on August 6, 7, and 8 still exist. At 02:00 on September 6, the backupgenerated on August 6 is deleted.



5.3 How Do I Back Up Multiple Resources at a Time?1. Log in to CBR Console and click Cloud Server Backup or Cloud Disk Backup

on the left navigation pane. On the displayed page, purchase a backup vault.It is recommended that the capacity of the vault be at least twice the totalsize of resources to be backed up.

2. Associate resources with the vault during or after the purchase.3. After the resources are associated, choose More > Perform Backup in the

Operation column of the target vault. You can manually back up two or moreresources at a time.Alternatively, you can set a backup policy for the vault. In this way, the systemwill automatically back up the associated resources at the scheduled time.



6 Others

6.1 Is There a Quota for CBR Vaults?No. You can create as many vaults as needed.

6.2 What Can I Do If the Vault Capacity Is Insufficient?Backup stops once the usage of the vault exceeds the upper limit. Take thefollowing measures when the storage capacity of your vault is insufficient:

1. Go to the target vault and delete unwanted backups.2. If you want to retain the generated backups, expand the vault. For details, see

Expanding a Vault.3. If a backup policy has been applied to the vault, disable the backup policy or

remove the policy from the vault. For details, see Disabling a Backup Policyand Removing a Policy from a Vault. Then, automatic backup is disabled,and the storage capacity of the vault will not change. Alternatively, you canprolong the automatic backup interval or reduce the number of backups to beretained by editing the backup policy, or reduce the number of serversassociated with the vault.

6.3 Will Backup Continue If the Usage of a VaultReaches the Upper Limit?

If the usage of a vault just reached the upper limit, or has not reached yet but itsremaining capacity is insufficient for the next backup, backup can still be executedfor once.

However, backup stops once the usage of the vault exceeds the upper limit.

6.4 Can I Export Disk Backup Data to Another Server?You can export disk backup data by creating a new disk using a disk backup andthen attaching the new disk to a server.

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6.5 Can I Download Backup Data to a Local PC?No. CBR backup data cannot be downloaded to a local PC.

6.6 How Do I Copy Disk Data to Another Account?If two accounts are in the same region, you can use backup sharing of CBR tocopy disk data to another account. For details, see Sharing a Backup. If twoaccounts are not in the same region, data sharing between accounts is notallowed.

6.7 What Should I Do If I Receive an Email or SMSMessage Indicating a Backup Failure?

If you receive an email or SMS message indicating a backup failure, a backup taskhas failed in one or more vaults in a region.

Log in to CBR Console, go to the region prompted in the email or SMS message,and check whether there are vaults whose progress bars in the Vault Capacitycolumn are displayed in red. If yes, take measures mentioned in What Can I Do Ifthe Vault Capacity Is Insufficient?.

There is a delay in sending emails. You will receive the notification email the nextday after the backup fails. If you have already expanded the vault capacity ortaken other measures before notifications are sent, just ignore the email.

Cloud Backup and RecoveryFAQs 6 Others



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cloud backup and recovery · 2020. 6. 14. · the backups generated by the original backup policy...

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