Storage for VDI


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This presentation, delivered by Howard Marks at Interop in Las Vegas May 2013 explores how system administrators can provide high performance storage for VDI implementations.

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  • 67% total say in next 12 months
  • 46% of all projects are stalled50% on cost or cost of storage, that 29% could be storage driven performance problems too
  • The Differencing or delta disk – The differencing disk is the key component of the linked clone. It is seen by the linked clone as its system disk, usually the C: drive for Windows systems. The differencing disk logs all the changes between this linked clone’s system disk and the master replica to which this clone is linked. The Internal Disk – A small virtual drive that holds identity information about the virtual PC including the SYSPREP or QUICKPREP configuration file and the password for the PC’s machine account in Active DirectoryThe Disposable Disk – The disposable disk for each linked clone holds temporary files that are needed only when the virtual PC is running. These files include the Windows swap file and optionally the user’s temp folder and temporary internet files folder. The contents of the disposable disk are deleted when the virtual PC is shutdown to save disk spaceAn optional Persistent Disk – formerly known as the user data disk, the persistent disk is presented to the clone’s operating system as an additional drive letter that can be used to store user data that should persist across refreshes of the differencing disk. 
  • View Persona management does partial copy on login EG:user registry. Rest fetched on use (network traffic)Only writes back changed files
  • So you need to look at Application virtualization, layering applicatons like Unidesk that are outside the scope of this talk
  • Caching replica disk only
  • Storage for VDI

    1. 1. Storage for VDIOr why storage vendors love VDI
    2. 2. VDI Looks Ready To Take OffWhen will you deployVDI?3 Months 3-6 Months6-9 Months 9-12 Months12+ MonthsHave you started a VDIpilot?54%46% YesNoSource: VIBriefing survey March 2012
    3. 3. But There’s a DisconnectReasons for VDI43%Better Endpoint ManagementLower cost"Cloud"SecurityReasons for VDI stall31%29%22%19%CostPerformanceSoftware LicensingStorage CostSource: VIBriefing survey March 2012
    4. 4. Desktop Virtualization Expenses4Source: Gartner Dataquest41%24%8%8%1%
    5. 5. 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 forknowledge workersVirsto sponsored survey of 500 IT professionals 3/2012
    6. 6. 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% ofthe VDI projects are stalled– Because of performance and/or cost
    7. 7. 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
    8. 8. VDI Presents Unique Workloads• Highly variable but coincident (boot/login in morning)• Steady state 50+% write200 Desktop VDI Storage Performance Demands
    9. 9. Anatomy of a Linked Clone• Master Replica– Common data• Delta Disk– Accumulates changesfrom master per clone• Disposable– Swap, Temp Etc.• Persistent (Opt)– Additional drive letter– Permanent data
    10. 10. Plus The Persona• Roaming Profile– Redirected USERSRacerX– Copied to C: on login– Issues:• Long login/logout• Disk space consumption– Especially on shared systems• More granular approaches like View PersonaManagement better
    11. 11. 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
    12. 12. 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.
    13. 13. 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
    14. 14. 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
    15. 15. View Storage Accelerator vs. BootStorm
    16. 16. And vs. AV Scan Storm
    17. 17. Atlantis ILIO• Dedupes data• Accumulates writes to 64KB• Larger read and write RAM Cache• Can install on each host or Top of Rack
    18. 18. 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 VDIsolutions• Local storage could be an answer– Especially for non-persistent clones– Consider local SSD, SSD caching RAIDcontroller
    19. 19. 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
    20. 20. 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
    21. 21. Server Side Caching State of The Art• Proximal Data, Flashsoft (Sandisk) install inhypervisor– 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
    22. 22. 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
    23. 23. 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 establishedvendors/products
    24. 24. Questions and Contact• Contact info:–– @DeepStoragenet on Twitter
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