Join virtualization expert and industry veteran Ron Oglesby as he discusses local storage vs centralized storage models for VDI, including the arguments for and against local storage in VDI environments, a review of converged platform models (ie Nutanix) for VDI, and SSD tips and tricks

1. GeekOn Discussion:
Local Disk vs ‘The SAN’
for
VDI Storage
Ron Oglesby @ronoglesby #GeekOn

2. Agenda
 Who cares about this session anyway?
 Why is disk so important in VDI?
 What are the key concepts to understand about VDI and
Storage
 Then…
 Why Local Storage rules for VDI
 Why Local Storage Blows and You should ONLY use SAN
storage for VDI

3. Disk for Desktops? Who cares?
 How many disks does it take to support 25 desktops?

4. Disk IO Understanding Limitations
Some References!
http://www.techrepublic.com/blog/datacenter/calc
ulate-iops-in-a-storage-array/2182
http://www.yellow-bricks.com/2009/12/23/iops/

5. Desktop IO Requirements?
 Read:Write ratio can be as high as 50:50
 60:40 to 70:30 is typical
 Light Users = 4-5 IOps
 Medium Users = 8-10 IOps
 Heavy Users = 14-20 IOps
 So if you have 50 medium users 400-500 Sustained IOps
 So if you have 75 users/server? 750 IO? 4 disks before
RAID penalty?! 8-10 or more after penalty?
 But what about boot / login storms?

6. Boot/Login Storms
 At boot and login IO can be extreme
 Even a medium user can generate 90-100 IO at login (why is
that 100 IO a ‘magic’ number?)
 Boot storms can be even worse
 The “good” thing about a boot storm is that it is
typically 90% Read!
 No RAID penalty
 Caching Helps
 Still must be planned for.

7. Disk Costs and VDI
 Dell 143 GB SAS 15K SAS Drive = $
 Dell 100 GB SSD Drive =$$
 EqualLogic SAS drives $$
 EqualLogic SATA drives = $
 EqualLogic SSD drives= $$$
 Windows 7 “Thick Provisioned” 20-35GB
 Windows 7 Linked-Clone = 8-10GB

8. Local Storage is the Solution
to this Problem

9. Local Storage
 Start with these questions:
 How many of you boot your normal desktops from
the SAN?
 How many of you boot your terminal servers from
the SAN?
 How many of you have an extremely short SLA on
recovering your desktops?

10. Why do people talk down local DAS
 Storage companies make a lot of money selling
centralized disk and the software around it. More
power to them!
 Hypervisor’s “BIG” features require centralized
storage- helps push all that higher end licensing
 Tools supplied by hypervisor vendors don’t work
without centralized storage.
Copyright © 2010 Unidesk Corporation. All Rights Reserved. www.unidesk.com

11. Local Storage is about Perf vs Cost
 Dell PCs can cost as little as $350!
 Performance requirements require High end disk
 Writable GB cost local vs SAN (SAS 15k)
 RAID 1 143GB Drives $5/GB – SAN 15K $10-30/GB
 Writable GB cost local vs SAN (SSD)
 RAID 1 143GB Drives $5/GB – SAN SSD $30-70/GB
 Why pay for centralized storage for a desktop?!

12. That’s ALL BS
SAN is the Solution to this
Problem
Local Storage is too limiting

13. Things this guy isn't telling you!
 HA, DRS, FT, E-I, E-I –OH…. Not available with local
disk!
 You might not even have enough spindles!
 Local/CHEAP SSD isn't that great.
 IO can be handle cost effectively on the SAN
 Storage Tiering/Data movement all but impossible
with local disk
 Dynamic Capacity/Cloud? Not happening with local
disk.
Copyright © 2010 Unidesk Corporation. All Rights Reserved. www.unidesk.com

14. All the features you love…
 Do I really need to detail them all?
 HA
 DRS
 FT
 SRM
 Storage vMotion
 Etc
 Etc

15. Spindle Count???
 50 users per server at 20 IO each= 1000 Iops
 100 users/server @ 10…
 Boot / Login Storms?
 RAID Penalty for writes?
 DL 360’s have 6 drive bays. 15K drives at 180 IO each
 1080 IOps before RAID penalty?
 Are you a Blade shop?
 Probably wont even get enough spindles in a server

16. “Cheap” SSD Issues
 So you move to SSD instead of rotating disk…
 $$$$ 149 GB SSD on Dell 610 $4,599.00
 $$ 100 GB SSD on Dell 610 $1,949.00
 Compare to 146GB at $359 on the same server.
 Can you even get enough writable space on those
SSD?
 Better to use SSD for just hot data rather than all data

17. Handle the IO with mixed disks
 Leverage Hybrid Arrays
 EqualLogic XVS
 EMC FAST Systems
 SSD / EFD can be used for HOT data
 Smart systems will MOVE the data
 Can also be used for writes!

18. What about that whole Dynamic Cloud?
 Data Tiering
 About placing data on the type of disk it NEEDS. Not fixed
provisioning
 Moving data from slow, to fast to REALLY fast disks
 Only moving small parts of data not whole VMDKs?!?!
 Elasticity in the VM environment
 Dynamic increases/decreases in capacity
 Provisioning times increase – sometimes dramatically
 Recovery and flexibility in the toilet

19. So what does Unidesk think?
 We don’t care….
 So what to we do?

20.  roglesby@unidesk.com
 @ronoglesby
Copyright © 2010 Unidesk Corporation. All Rights Reserved. www.unidesk.com

21. Open Q&A