1. Accelerate VDI - VSA Based I/O
Designs
Daniel Beveridge
Sr. View Architect
Vmware.

2. Storage Sizing
Conundrum
How Much to
Buy?
The Storage Guessing Game
•Save Money •Unsure How Many Users
•Unsure How Many Users •Overestimate ramp rate
•Misunderstand IOPS/user •Misjudge process hurdles
•Unsure of Project timeline •Use of Legacy storage
•Spend on Space vs. IOPS

3. The Result – Declining
User Experience

4. Workload basics: Comparing
Server to Desktop
Server Desktop
Diversity on cluster Homogeneous on cluster
Peaks randomized across apps Synchronized peaks
App driven I/O User driven I/O
Maintenance is manual or targeted Maintenance is often synchronized on
many machines
Batch-oriented Real-time oriented
Performance fluctuations have low to Performance fluctuations have high
moderate visibility and impact visibility and real-time impact
Low to moderate workload volatility (peak High workload volatility (peak > 50x avg)
< 10x avg)
 Key differences between workloads
• Vastly different volatility
• Users react in real-time to performance fluctuations
• Severity of reaction to performance fluctuations

5. Volatility Examples – High and Low
High Volatility (VDI)
Low Volatility (Server)

6. VDI Volatility – Logon IOPS
* Graph by Jim Moyle

7. Windows 7
Implications
• Up to 40% more IOPS than XP during select
operations such as boot.
• Boot operations consume about 100 IOPS on
average
• Select optimizations are possible to brings IOPS
consumption more inline with XP
• Most customers will use a Win 7 build that is not
optimized. Sizing estimates should not assume
Win 7 image is tuned properly.
• Win 7 deployments need the additional IOPS
provided by VSA accelerated storage designs.

8. Traditional VDI Designs

9. Virtual Storage Appliance (VSA)
based Design w/View 4.5

10. Why VSA Storage for VDI?
• Very Flexible ‘hardware’ configuration
• Drivers taken care of by VMware HCL
• Low latency I/O delivery to desktops
• Limit need for costly networking equipment
• Handles random writes very well – VDI’s most
challenging load pattern
• It’s software – easy to upgrade, re-tune using
automation tools.

11. Benefits of VSA based Designs
Benefits Importance
Inexpensive Storage Cost per User drops
High IOPS / User (30k+) Great User Experience
Burst Isolation Equitable Burst Access
Low Latency (1/10ms) Great User Experience
Minimizes Network Traffic Lowers risk of bottlenecks
Uniform IOPS/User at any Eliminates declining user
Scale experience on ramp-up.
Scalable Write-Cache Great User Experience – fast
writes at any scale
Reduce random writes to SSD ACK from RAM for stateless

12. VDI – Two Models
• Stateless – Users are decoupled from VMs
– Most performance benefits
– Most operational savings
– Most amenable to a purely local disk design
– Least expensive, but may require re-working of IT processes leading to
implementation challenges
• Persistent – Users have their own VM
– Uses much more storage
– Desktop must be ‘protected’ against data-corruption
– Writes must be treated conservatively – limiting performance
– More challenging for VSA designs

13. Stateless VDI - Benefits
General Benefits Benefits of Stateless w/ZFS
• Zero risk of desktop corruption
• Ability to maximize fast random • Ability to Maximize limited local disk
writes (ACK from Ram) – best user resources
experience for random writes • Efficient two drive bay config (1 SSD, 1
• Lends itself to a local disk design HDD)
• Keep all I/O inside ESX host. • Ability to maximize fast random writes
• Enables use of View Composer (ACK from Ram)
• Avoid Windows Configuration drift • In-line compression expand disk
• Limit support calls – standard image bandwidth 40%
for everyone • L2ARC leverages modest SSD without
• Faster support resolution times running out of space
• Reduce # of VDI machines powered • Excellent caching with ARC
on in datacenter
• Lowest cost per user

14. VDI Design Options – Stateless VDI
Design Hints
• Create VMDK for L2ARC on SSD
ZFS VSA • Disable ZIL – not needed
• Publish volume via NFS to ESX
• 8-12GB memory for VSA
• CPU / memory reservation for VSA
• Set pool policy to ‘refresh’ at
logoff
Local Disks Sample 64GB SSD Format
SSD • 15GB for View’s Composer
parent image
• 40GB VMDK for L2ARC
HDD

15. Persistent VDI - Benefits
General Benefits Benefits of Stateless w/ZFS
• Ability to Maximize limited
• Least Operational upheaval when local disk resources
migrating from PC model • Efficient two drive bay config
• Supports user-installed (1 SSD, 1 HDD)
applications • Ability to maximize fast
• Works better for ‘offline-VDI’ random writes (ACK from ZIL)
feature of VMware View • In-line compression expand
disk bandwidth 40%
• In-line De-Dupe – 2.5x data
reduction
• L2ARC leverages modest SSD
without running out of space
• Excellent caching with ARC

16. VDI Design Options – Persistent VDI
All Local Design
Design Hints
• Create VSA’s VMDK ‘data disk’ on SAN/NAS via iSCSI
of FC
• Place ‘data disk’ ZVOL on local HDD in Raidz mirror
• Create VMDK for L2ARC on SSD
• Place ZIL (SLOG) on SSD
• Publish volume via NFS to ESX
• 12-16GB memory for VSA
• Assign CPU / memory reservation
ZFS VSA • Turn on De-Dupe and Compression
• Sample 64GB SSD Config: 8GB ZIL, 50GB L2ARC
Benefits / Drawbacks
• VDI clients get fast local commits on write due to
SSD based ZIL (ZFS intent Log)
• VSA can 50 write IOPS per user for 150+ users with 1
SLC based SSD as ZIL, and 100+ read IOPS per user.
• Inline De-Dupe & Compression reduce I/O from VSA
HDD(s) by 80% - better use of limited spindles.
ZIL Approximately 30K+ IOPS possible from VSA
SSD •
• Longer RTO in failure – Host rebuild may be needed
L2ARC
ZVOL HDD

17. VDI Design Options – Persistent VDI
Hybrid Design
Design Hints
SAN/NAS • Create VSA’s VMDK ‘data disk’ on SAN/NAS via
iSCSI or FC
• Place VSA boot drive on SAN/NAS
• Create VMDK for L2ARC on SSD
• Place ZIL (SLOG) on SSD
iSCSI or FC
attached VMDK
• Publish volume via NFS to ESX
• 12-16GB memory for VSA
ZFS VSA • Assign CPU / memory reservation
• Sample 64GB SSD Config: 8GB ZIL, 50GB L2ARC
Benefits
• High # of low-latency random write IOPS possible
from VSA with local ZIL, 30K+ Read IOPS.
• VDI clients get fast local commits on which makes
a great user experience
• Inline De-Dupe & Compression reduce I/O from
VSA to SAN/NAS by 80%
ZIL • Data safer in Host failure scenario – Shorter RTO
SSD • May need to move SSD to new ESX host in failure
L2ARC scenario

18. Isn’t this all a bit Complex?
• Different and intricate ZFS configs base on VDI pool type
– ZIL status, size, L2ARC size, Raid-z status, De-Dupe/Compress??, hybrid
VSA/Central config?
• Sizing & Tuning Complexity – How much memory/CPU and other vSphere
tuning parameters are needed for each option?
– CPU/IO/Mem reservations?, type of VMDK (thin, fat, eager zero?),
– iSCSI or NFS mount to ESX?
• How does your OS image impact these tunings?
– Are there wasteful services running ?
– Did a new application change your I/O load levels?
• Wow – there’s a lot of steps involved to set this all up?
– I feel Carpel tunnel coming on!!
I want to use this cool technology – how can it be easier?

19. Help is on the way
The Nexenta VDI Solution
• Setup a whole vSphere cluster – VSA & VDI together in one
place
• Using ‘provisioning templates’, just answer some simple
questions and the rest is taken care of for you.
• Pairs ideal ZFS tunings for each VMware View Pool type
• Calculates correct resource levels for VSA based on user
density targets.
• Optimizes VDI density based on IOPS targets you can set.
• Runs built-in Micro-Benchmarks to validate performance
• Deploy View with confidence and ease – removes the tedious
steps and assures an optimized solution.

20. Design Principles for
Maximizing VDI Benefits
1. Divide Use Cases into Stateless vs. Persistent
• Leverage VMware tools like ThinApp to maximize users who qualify
for stateless designs – use local VSA storage for these users.
• Use VMware’s Virtual Profile tool to keep data out of VM
2. Push as much I/O delivery upstream to VSA as possible
• Maximize value of centralized storage for high value IO (offload
junk IOPS).
• Hybrid VSA/Central storage design for persistent VDI
3. Integration with VMware View’s Tiered Storage
• Leverage centralized SSD or local replica for shared OS image when
using View Composer
• Maximize caching of VSA(s) for unique user files.
• Place View’s ‘disposable disk’ on ZVOL with ZIL disabled for
persistent VDI VMs
• Reduce Logon Storm I/O & data risk with our Virtual Profile
feature

21. Summary
• ZFS features are very well suited to implementing VSA designs for VDI
• Key Features include: ZIL, L2ARC, De-Dupe, Compression, ARC caching, Raid-z.
• Hybrid VDI design combining SAN/NAS with VSA accelerates I/O, lowers
cost
• A scale-out VSA storage model to augment SAN/NAS can lower risk of
under/over spending by transforming CAPEX into incremental spend.
• Use centralized storage for important data, high value I/O and persistent
VDI designs. Use local storage for disposable data & non-persistent VDI
Last but NOT Least: Look for Nexenta’s exciting new VDI provisioning
solution to dramatically simplify the deployment of VSA storage and
VMware View desktops (Q1 2012?)