Backup Compression and Storage Deduplication: A perfect match?

Hosted by David Gugick &

David Swanson, Dell Software

June 27, 2013

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Agenda

• Speaker Introductions

• Deduplication Explained

• Deduplication and Backup Compression Benefits

• Ingest Rates

• Backup Recommendations

• Real-World Performance

• Takeaways

• Q & A

• Resources

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David Swanson

• Database Systems Consultant, Dell Software

• david.swanson@software.dell.com

David Gugick

• Product Management, Data Protection, Dell Software

• david.gugick@software.dell com

• @davidgugick

Your Hosts

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Deduplication Explained • Eliminates the need to save duplicate data

• Connections – CIFS, NFS, Proprietary (DD Boost, Dell RDA)

• Inline vs post-process – Max ingest rate (single stream vs aggregate)

• Find matches – Chunking – sliding windows / variable block

size

• Compress

• Target vs source-side deduplication

• Software vs hardware solutions

• Read Speed (Rehydration) – Overhead varies by vendor

• Replication

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Deduplication Effectiveness Varies

• Variables that influence the dedupe ratio for a given workload include: – The type of data being backed up: Not all data sets have the same amount of duplicate data or

compressibility – The frequency of backups: More frequent backups will build the dedupe dictionary more quickly – The retention period for backup jobs: Longer retention yields higher ratios – The types of backups: Full backups will dedupe better than differential or transaction log backups

• Estimated deduplication ratio – Ratio estimates range from 9-12:1 for databases – same as 90-92% compression – Not a lot of duplicate data between databases – Benefits with databases are largely due to chunk matches within a single database

• Retention recommendations – Keep only what you need: Don’t keep more backups simply to raise the ratios

• Full or differential backups? – Most vendors will estimate logical storage (dedupe ratios) based on whether the customer

performs full backups or leverages differential / incremental backups

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Deduplication Benefits

• Storage is reduced

• Replication speeds improve

• Processing is moved from servers to storage

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Backup Compression Benefits

• Reduces or eliminates disparity between source and target disk speeds – Backup speeds improve

– Restore speeds improve

• Storage is reduced

• Network utilization is reduced

• Replication speeds improve

• Dump to and restore from tape speeds improve

• Helps with initializing Log Shipping / Mirroring / AlwaysOn Availability Groups

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Ingest Rates

• Max ingest rate determines how fast the device can consume data – Many times stats are based on multiple backup streams

– Single stream performance may be lower

– Varies widely by how much you spend

• Network plays an important part – In practice, limits are lower

– 1 Gb = 125 MB / Sec

– 10 Gb = 1.25 GB / Sec

– Fibre Channel (8 GFC) = 1.6 GB / Sec

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• Offset backups to avoid network and ingest rate contention

• Test with and without compression – Try a low-CPU compressor – 85% compression gives you close

to 7X the write bandwidth

• Consider using differential backups to reduce storage and backup time

– 70% reduction in data backed up means backups run on average 3.3X faster

Backup Recommendations

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Backup Speed – 1 Backup

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Backup Speed – 2 Parallel Backups

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Backup Speed – 3 Parallel Backups

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Restore Speed

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Storage Footprint

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Takeaways

• Backup compression and deduplication are a good match

• Test your environment – Your results will vary based on many factors including: Rated speed of appliance, network

design, backup job coordination, compressibility of the database, database data change rate

– Don’t expect much deduplication between different databases – most of the benefits are gained from backups of the same database

• Deduplication storage appliances are almost always shared in an environment – A single test on a single database in the lab is not representative of production – Furthermore, running full backups on the same database 30 times in a row as a test is not

representative of production either – Even with exclusive access to deduplication storage by DBA team, there will usually be

contention from parallel backup streams

• You won’t know the full effect of performing uncompressed backups until you test – Maintenance windows and RTOs may be affected

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Takeaways

• Test using lightweight backup compression – Avoids CPU load on the database server – Allows the deduplication storage the opportunity for some extra dedupe – Avoid Adaptive Compression to maximize deduplication

• If backup and restore times are most important, don’t be concerned with actual storage consumed

– At worst, it’s a wash. At best, you’re saving space with compression – Don’t be overly concerned with final deduplication ratios - don’t keep 30 days of backups

for each db just to get better deduplication ratios if you only need 14 days

• Consider reducing data backed up using differential backups – Reduces the data read from SQL Server, sent over the network, and processed by the

storage – Reduced backup windows – Can be compressed just the same

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Q & A

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Resources - References • Some Deduplication Resources

– Demystifying Deduplication White Paper: http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/demystifying-deduplication.pdf

– Why Dedupe is a Bad Idea for SQL Server Backups: http://www.brentozar.com/archive/2009/11/why-dedupe-is-a-bad-idea-for-sql-server-backups/

– Backup Compression and Deduplication blog posts: http://communities.quest.com/community/data-protection/blog/2012/04/05/backup-compression-and-deduplication-good-or-bad

• LiteSpeed – LiteSpeed Landing Page: http://www.quest.com/litespeed-for-sql-server/ – Tech Brief: Top 7 LiteSpeed Features DBAs Should Know About:

http://www.quest.com/techbrief/top-6-litespeed-features-dbas-should-know-about815805.aspx

– Webcasts and Events: http://www.quest.com/events/list.aspx?contenttypeid=15&prod=192

• Dell DR4100 – http://www.dell.com/us/business/p/dell-dr4100/pd

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Thanks