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IOPS requirements
A customer asked me if we have a general rule of thumb for scoping Iops for VDI. For example, X VDI desktops require Y Iops (assuming basic MS Office use)
Does anyone have general rule of thumb?
Michel Roth
173 Posts
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September 3rd, 2010 13:00
IOPS scaling, like bandwidth ( and to a lesser extent CPU scaling) is a very hard and exact science.
Just providing averages is deadly but designing to accommodate all the bursts is too expensive. So you will end up somewhere in the middle. That middle differs per customer. Taking averages can be risky. More experienced implementation partners will tell you about the importance of being able to accommodate bursts.
One important thing to remember is that windows xp is quite different from windows 7.
DELL-Jon Ro
64 Posts
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September 3rd, 2010 14:00
I get that, but can you at least give me some typical numbers? I've heard some tests requring as little as 3 IOPS per virtual desktop. Is that typical?
Michel Roth
173 Posts
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September 17th, 2010 15:00
It also depends on the VM state. These number provide a good average:
This depends on many factors and also the read/write ratio is very important!
dbolton
180 Posts
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September 21st, 2010 13:00
Is a good average.... in our testing I've found "work loads" to be anything between 3 and 15 for small - medium system usage. I've noticed Windows 7 booting ranges between 15 - 33 though.
I'm guessing with emerging technologies such as RemoteFX, IOP requirements will increase as more demanding applications will start hammering the disks.
Though all this depends on use case.
Other things can come into play to, disk type, storage type, raid level, speed, virtual disk alignment, etc etc.
I agree with Michel, averages are risky!
3 IOPs is generally windows twiddling it's thumbs wondering how to fill the time
Dan.
Michel Roth
173 Posts
0
September 21st, 2010 18:00
Hi Dan,
Did you get also get a chance to compare the read/write ratios for these different areas of a VD session?
ssloan1
11 Posts
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September 21st, 2010 19:00
Cisco has some pretty indepth white papers on this. Granted...it's in reference to selling their UCS line, but good testing numbers nonetheless.
dbolton
180 Posts
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September 21st, 2010 20:00
Hi Michel,
Nope... Using my own session on a Win7 VM and based on work load only, so no boot, login or logout ratios....
I would say R=20 - 30% and write is 70 - 80% over the course of a 2 hour session doing everything from web browsing to dreamweaver.
"They" say 20r - 80w is the average so I guess mines not to far off.
If I get chance I'll look into the different sections in the next week or so. - I've I remember
Cheers,
Dan.
dbolton
180 Posts
0
September 21st, 2010 20:00
Just to add... As we're using local storage for non-persistent VM's (which will count for 99.9% of our VM's), IOPs haven't been an issue for us as the servers we're using can cope with the IOPs per hosted VM. Our IOPs are spread across our hosts rather than central storage.
The headache comes when you have to make sure your SAN can cater for VDI VM's at a large scale and also make sure it's financially sustainable to scale out.
Of course this all comes down to architecture design, brick vs blade, etc...
I digress, thats for another thread
Cheers,
Dan.
PatrickRAtDell
37 Posts
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September 22nd, 2010 00:00
Daniel, can you please share your server hardware configuration, i.e. make, model, CPU type & quantity, amount and type of RAM, number od local disks, type, speed, type of RAID Controller, amount of battery backed or flash cache, NIC Configuration, hypervisor type and version. I like to have cuistomer proven setups as reference to validate what we see in the lab.
Thanks.
dbolton
180 Posts
0
September 22nd, 2010 06:00
Hi Patrick,
This is what I can tell you from home (not back in the office until Monday)...
Spec as follows:
----------------
IBM System x3650 M3 (2U)
NetXtreme II 1000 Express Quad Port Ethernet Adapter
12 X IBM 146GB 15K 6Gbps SAS 2.5" SFF Slim-HS HDD
2 X IBM 74GB 10K 6Gbps SAS 2.5" SFF Slim-HS HDD
IBM System x3650 M3 8 HDD Kit,1
Hot-swap SAS SATA 8 Pack HDD Enablement Kit (w/ 6 Gbps expander)
ServeRAID M5015 SAS/SATA Controller
ServeRAID M5000 Series Battery Assembly
2 X Intel Xeon Processor X5650 6C 2.66GHz 12MB Cache 1333MHz 95w
6 X 4GB PC3L-10600 CL9 ECC DDR3 1333MHz LP RDIMM
12 X 8GB PC3L-10600 CL9 ECC DDR3 1333MHz LP RDIMM
IBM UltraSlim Enhanced SATA Multi-Burner
Dual port 1Gb Ethernet Daughter Card,1
IBM System x3650 M2 & M3 R2 PCI-Express (2x8) Riser Card
IBM System x3650 M2 & M3 R2 PCI-Express (1x16) Riser Card 2
IBM 675W Redundant AC Power Supply
----------------
We're using Hyper-V R2 as the hypervisor which is installed on the 2 10k disks.
The VM's are on the 12 15K drives using Raid 10
We're getting between 40 - 55 Windows 7 VM's and 1 RDSh server which is catering for 20 - 30 users (and I think it can do more).
In our rough estimations (on a flip chart), hosting 30 - 35 VM's and the RDS VM with 10 - 15 users pretty much brakes even financially. Above these numbers, we see a ROI. Adding SAN to the mix is another story though....
We plan to add FX GFX cards to each server for RemoteFX (when it comes out) so that pushes the ROI down a little but it's still there.
Bare in mind we are public sector and do get good hardware/software discounts!
Cheers,
Dan.
Michel Roth
173 Posts
0
September 22nd, 2010 07:00
Hi Dan,
Interesting. Do you know what the theoretical IOPS capacity is for the IBM 146GB 15K 6Gbps SAS 2.5" SFF Slim-HS HDD?
Michel Roth
173 Posts
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September 22nd, 2010 07:00
Hi Shawn,
Do you have a link to this paper?
dbolton
180 Posts
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September 22nd, 2010 08:00
Yep but not off the top of my head
I'll dig it out ASAP It's written in my notes... Why don't vendors ever have this info easily available on their site!
DELL-Robb S
22 Posts
0
September 24th, 2010 00:00
This was in a MS guide to scaling vdi for Win7
Read
Write
Read+Write
Mbytes/sec
Ops/sec
Mbytes/sec
Ops/sec
Mbytes/sec
Ops/sec
Avg
Peak
Avg
Peak
Avg
Peak
Avg
Peak
Avg
Peak
Avg
Peak
64 users
10
220
350
2500
8
75
350
2500
18
224
700
3500
dbolton
180 Posts
0
September 24th, 2010 06:00
Is that after "tweaking" the OS first? or is it a non-molested OS?
It goes to show though that local storage is very very compelling
Cheers,
Dan