Storage for VDI

Or why storage vendors love VDI

VDI Looks Ready To Take Off

When will you deploy VDI?

3 Months 3-6 Months6-9 Months 9-12 Months12+ Months

Have you started a VDI pilot?

54%

46% Yes

No

Source: VIBriefing survey March 2012

But There’s a Disconnect

Reasons for VDI

43%

Better Endpoint ManagementLower cost"Cloud"Security

Reasons for VDI stall

31%

29%

22%

19%

Cost Performance

Software Licensing Storage Cost

Source: VIBriefing survey March 2012

Desktop Virtualization Expenses

4

Source: Gartner Dataquest

41%24%

8%8%

1%

Everyone’s Talking VDI

• 76% are choosing VDI to:– Save Costs– Improve management

• 54% project total cost <$500– One writer claimed <$200 VDI cost

• 80% Prefer persistent desktops for knowledge workers

Virsto sponsored survey of 500 IT professionals 3/2012

The Sad Truth

• Most success stories are task workers– Call centers, healthcare, Etc

• Much of your desktop support is user support• Enterprise storage is expensive• VDI creates high IOP density• According to that same Virsto study, 46% of

the VDI projects are stalled – Because of performance and/or cost

VDI and Storage

• Desktop disk:– 30-40GB, 100 IOPS – 200 desktops = 6TB, 20,000 IOPS– 100+ 15K RPM drives RAID 10

• Windows 7 with AV 2x IOPS of WinXP• VDI user steady state IOPS

– Light 6-12– Power 5-40

• But you need to plan for peak

VDI Presents Unique Workloads

• Highly variable but coincident (boot/login in morning)• Steady state 50+% write

200 Desktop VDI Storage Performance Demands

Anatomy of a Linked Clone• Master Replica

– Common data

• Delta Disk – Accumulates changes

from master per clone

• Disposable– Swap, Temp Etc.

• Persistent (Opt)– Additional drive letter– Permanent data

Plus The Persona• Roaming Profile

– Redirected \USERS\RacerX– Copied to C: on login– Issues:

• Long login/logout• Disk space consumption

– Especially on shared systems

• More granular approaches like View Persona Management better

About Desktop Persistence

• Non-Persistent desktops– Delta disk discarded at shutdown/logout– For task workers

• Persistent linked clones– Preserve delta disk, persistent disk– Allows centralized patching via re-composition

• Full clones– Complete virtual PC

Living with Linked Clones

• Constant growth– At VMware 1GB/user/week– Can overwhelm initial savings

• IOP concentration on Master Replica– Good use of a little flash

• Recomposing resets non-persona data– Installed Applications

• Browser plugins, Etc.

Basic VDI Recommendations

• Use linked clones or deduped full clones• Put master image on flash (many reads)

– More IOPS to Delta during steady state though

• Separate differencing data– User profiles– Swaps

• Try to avoid IOPS to spinning disk– Use RAM or flash

• $/IOP not $/GB

View Storage Accelerator

• AKA Content Based Read Cache• Up to 2GB RAM as a read cache• Content Based means cache is deduped • Most effective at boot

– Cause that’s when lots of common data reads

View Storage Accelerator vs. Boot Storm

And vs. AV Scan Storm

Atlantis ILIO

• Dedupes data• Accumulates writes to 64KB• Larger read and write RAM Cache• Can install on each host or Top of Rack

The Good News

• VDI Images are just desktops– HA may be less important than performance– I would use a single controller Flash system

• All the storage startups are validating VDI solutions

• Local storage could be an answer– Especially for non-persistent clones– Consider local SSD, SSD caching RAID

controller

Things to look for in VDI Storage

• Substantial flash component – 10% or more– All flash for cast of thousands

• Good snapshots– EG: Nimble, TinTri, NetApp

• VAAI Xcopy integration• Data Deduplication

– Greenbytes, Pure, Astute for all flash– TinTri, Tegile, Nexgen hybrids

Server Flash Caching Advantages

• Take advantage of lower latency– Especially w/PCIe flash card/SSD

• Data written to back end array– So not captive in failure scenario

• Works with any array– Or DAS for that matter

• Allows focused use of flash– Put your dollars just where needed– Match SSD performance to application

• Politics: Server team not storage team solution

Server Side Caching State of The Art

• Proximal Data, Flashsoft (Sandisk) install in hypervisor– But are write through cache

• Speeds reads but passes writes through

• Most others are server only (agent based)• Write back is coming

– Will write to SSD in n servers (n=2-3)– Will require low latency net – PernixData 1st more coming

Full Clones and Deduplication

• Full clones manage like desktops– Good news if you manage desktops

• But most people don’t use Kace or LANdesk

• Full clones are fully persistent • Deduplication reduces swap space too

– 100 new linked clones = 200GB swap reserve

• Flash eliminates read performance penalties• Inline better than post process for live data

The Don’ts

• Don’t use RAID-5 spinning disks for VDI– VDI workloads have lots of small writes– RAID-5 amplifies 3-6:1

• Expect an all disk solution to serve >50 users– Conventional wisdom = dedicated storage

• Expect $100/user costs• Limit your options to established

vendors/products

Questions and Contact

• Contact info:– Hmarks@deepstorage.net – @DeepStoragenet on Twitter