Ceph: a decade in the making and still going strongSage Weil

Today the part of Sage Weil will be played by...

RESEARCH

INCUBATIONRESEARCH

INKTANKINCUBATIONRESEARCH

Research beginnings

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RESEARCH

UCSC research grant

● “Petascale object storage”● DOE: LANL, LLNL, Sandia

● Scalability, reliability, performance

● HPC file system workloads

● Scalable metadata management

● First line of Ceph code● Summer internship at LLNL

● High security national lab environment

● Could write anything, as long as it was OSS

The rest of Ceph

● RADOS – distributed object storage cluster (2005)

● EBOFS – local object storage (2004/2006)

● CRUSH – hashing for the real world (2005)

● Paxos monitors – cluster consensus (2006)

→ emphasis on consistent, reliable storage

→ scale by pushing intelligence to the edges

→ a different but compelling architecture

Industry black hole

● Many large storage vendors● Proprietary solutions that don't scale well

● Few open source alternatives (2006)● Very limited scale, or

● Limited community and architecture (Lustre)

● No enterprise feature sets (snapshots, quotas)

● PhD grads all built interesting systems...● ...and then went to work for Netapp, DDN, EMC, Veritas.

● They want you, not your project

A different path?

● Change the storage world with open source● Do what Linux did to Solaris, Irix, Ultrix, etc.

● License● LGPL: share changes, okay to link to proprietary code

● Avoid unfriendly practices● Dual licensing

● Copyright assignment

● Platform● Remember sourceforge.net?

Incubation

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INCUBATIONRESEARCH

DreamHost!

● Move back to LA, continue hacking

● Hired a few developers

● Pure development

● No deliverables

Ambitious feature set

● Native Linux kernel client (2007-)

● Per-directory snapshots (2008)

● Recursive accounting (2008)

● Object classes (2009)

● librados (2009)

● radosgw (2009)

● strong authentication (2009)

● RBD: rados block device (2010)

The kernel client

● ceph-fuse was limited, not very fast

● Build native Linux kernel implementation

● Began attending Linux file system developer events (LSF)● Early words of encouragement from ex-Lustre dev

● Engage Linux fs developer community as peer

● Initial attempts merge rejected by Linus● Not sufficient evidence of user demand

● A few fans and would-be users chimed in...

● Eventually merged for v2.6.34 (early 2010)

Part of a larger ecosystem

● Ceph need not solve all problems as monolithic stack

● Replaced ebofs object file system with btrfs● Same design goals; avoid reinventing the wheel

● Robust, supported, well-optimized

● Kernel-level cache management

● Copy-on-write, checksumming, other goodness

● Contributed some early functionality● Cloning files

● Async snapshots

Budding community

● #ceph on irc.oftc.net, ceph-devel@vger.kernel.org

● Many interested users

● A few developers

● Many fans

● Too unstable for any real deployments

● Still mostly focused on right architecture and technical solutions

Road to product

● DreamHost decides to build an S3-compatible object storage service with Ceph

● Stability● Focus on core RADOS, RBD, radosgw

● Paying back some technical debt● Build testing automation

● Code review!

● Expand engineering team

The reality

● Growing incoming commercial interest● Early attempts from organizations large and small

● Difficult to engage with a web hosting company

● No means to support commercial deployments

● Project needed a company to back it● Fund the engineering effort

● Build and test a product

● Support users

● Orchestrated a spin out of DreamHost in 2012

Inktank

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INKTANKINCUBATIONRESEARCH

Do it right

● How do we build a strong open source company?

● How do we build a strong open source community?

● Models?● Red Hat, SUSE, Cloudera, MySQL, Canonical, …

● Initial funding from DreamHost, Mark Shuttleworth

Goals

● A stable Ceph release for production deployment● DreamObjects

● Lay foundation for widespread adoption● Platform support (Ubuntu, Red Hat, SUSE)

● Documentation

● Build and test infrastructure

● Build a sales and support organization

● Expand engineering organization

Branding

● Early decision to engage professional agency

● Terms like● “Brand core”

● “Design system”

● Company vs Project● Inktank != Ceph

● Establish a healthy relationship with the community

● Aspirational messaging: The Future of Storage

Slick graphics● broken powerpoint template 29

Traction

● Too many production deployments to count● We don't know about most of them!

● Too many customers (for me) to count

● Growing partner list

● Lots of buzz

● OpenStack

Quality

● Increased adoption means increased demands on robust testing

● Across multiple platforms● Include platforms we don't use

● Upgrades● Rolling upgrades

● Inter-version compatibility

Developer community

● Significant external contributors

● First-class feature contributions from contributors

● Non-Inktank participants in daily stand-ups

● External access to build/test lab infrastructure

● Common toolset● Github

● Email (kernel.org)

● IRC (oftc.net)

● Linux distros

CDS: Ceph Developer Summit

● Community process for building project roadmap

● 100% online● Google hangouts

● Wikis

● Etherpad

● First was in Spring 2013, 7th just completed

● Great feedback, growing participation

● Indoctrinating our own developers to an open development model

And then...

s/Red Hat of Storage/Storage of Red Hat/

Calamari

● Inktank strategy was to package Ceph for the Enterprise

● Inktank Ceph Enterprise (ICE)● Ceph: a hardened, tested, validated version

● Calamari: management layer and GUI (proprietary!)

● Enterprise integrations: SNMP, HyperV, VMWare

● Support SLAs

● Red Hat model is pure open source● Open sourced Calamari

The Present

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Tiering

● Client side caches are great, but only buy so much.

● Can we separate hot and cold data onto different storage devices?

● Cache pools: promote hot objects from an existing pool into a fast (e.g., FusionIO) pool

● Cold pools: demote cold data to a slow, archival pool (e.g., erasure coding, NYI)

● Very Cold Pools (efficient erasure coding, compression, osd spin down to save power) OR tape/public cloud

● How do you identify what is hot and cold?

● Common in enterprise solutions; not found in open source scale-out systems

→ cache pools new in Firefly, better in Giant, continued in Hammer

Erasure coding

● Replication for redundancy is flexible and fast

● For larger clusters, it can be expensive

● We can trade recovery performance for storage

● Erasure coded data is hard to modify, but ideal for cold or read-only objects

● Cold storage tiering

● Will be used directly by radosgw

Storage overhead

Repair traffic

MTTDL (days)

3x replication 3x 1x 2.3 E10

RS (10, 4) 1.4x 10x 3.3 E13

LRC (10, 6, 5) 1.6x 5x 1.2 E15

Erasure coding (cont'd)

● In firefly

● LRC in Giant

● Intel ISA-L (optimized library) in Giant, maybe backported to Firefly

● Talk of ARM optimized (NEON) jerasure

Async Replication in RADOS

● Clinic project with Harvey Mudd

● Group of students working on real world project

● Reason the bounds on clock drift so we can achieve point-in-time consistency across a distributed set of nodes

CephFS

● Dogfooding for internal QA infrastructure

● Learning lots

● Many rough edges, but working quite well!

● We want to hear from you!

The Future

43

CephFS

→ This is where it all started – let's get there

● Today● QA coverage and bug squashing continues

● NFS and CIFS now large complete and robust

● Multi-MDS stability continues to improve

● Need● QA investment

● Snapshot work

● Amazing community effort

The larger ecosystem

Storage backends

● Backends are pluggable

● Recent work to use rocksdb everywhere leveldb can be used (mon/osd); can easily plug in other key/value store libraries

● Other possibilities include LMDB or NVNKV (from fusionIO)

● Prototype kinetic backend

● Alternative OSD backends● KeyValueStore – put all data in a k/v db (Haomai @ UnitedStack)

● KeyFileStore initial plans (2nd gen?)

● Some partners looking at backends tuned to their hardware

Governance

How do we strengthen the project community?

● Acknowledge Sage's role as maintainer / BDL

● Recognize project leads● RBD, RGW, RADOS, CephFS, Calamari, etc.

● Formalize processes around CDS, community roadmap

● Formal foundation?● Community build and test lab infrastructure (getting IPs this

week!)

● Build and test for broad range of OSs, distros, hardware

Technical roadmap

● How do we reach new use-cases and users?

● How do we better satisfy existing users?

● How do we ensure Ceph can succeed in enough markets for business investment to thrive?

● Enough breadth to expand and grow the community

● Enough focus to do well

Performance

● Lots of work with partners to improve performance

● High-end flash back ends. Optimize hot paths to limit CPU usage, drive up IOPS

● Improve threading, fine-grained locks

● Low-power processors. Run well on small ARM devices (including those new-fangled ethernet drives)

Ethernet Drives

● Multiple vendors are building 'ethernet drives'

● Normal hard drives w/ small ARM host on board

● Could run OSD natively on the drive, completely remove the “host” from the deployment

● Many different implementations, some vendors need help w/ open architecture and ecosystem concepts

● Current devices are hard disks; no reason they couldn't also be flash-based, or hybrid

● This is exactly what we were thinking when Ceph was originally designed!

Big data

Why is “big data” built on such a weak storage model?

● Move computation to the data

● Evangelize RADOS classes

● librados case studies and proof points

● Build a general purpose compute and storage platform

The enterprise

How do we pay for all our toys?

● Support legacy and transitional interfaces● iSCSI, NFS, pNFS, CIFS

● Vmware, Hyper-v

● Identify the beachhead use-cases● Only takes one use-case to get in the door

● Single platform – shared storage resource

● Bottom-up: earn respect of engineers and admins

● Top-down: strong brand and compelling product

Why we can beat the old guard

● It is hard to compete with free and open source software● Unbeatable value proposition

● Ultimately a more efficient development model

● It is hard to manufacture community

● Strong foundational architecture

● Native protocols, Linux kernel support● Unencumbered by legacy protocols like NFS

● Move beyond traditional client/server model

● Ongoing paradigm shift● Software defined infrastructure, data center

Thanks!