Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage (1139 Views)
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Frequent Advisor
Erick Arturo Perez
Posts: 73
Registered: ‎02-28-2008
Message 1 of 7 (1,169 Views)

Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

Hi there, 

 

there is an installation that has 2xBK716B (HP Lefthand P4300 G2 (16) 450 GB 6G 15K LFF Dual-port ENT SAS) at 10Gbps iscsi being used by a HP c7000 chasis with 4 BL460c blades connected to the storage via iscsi. The c7000 and the blades dont have FC ports since all was done via iSCSI.

 

And we now want to implement 500 VDI (golden image + non persistent desktops) (win7). Since we have no metrics to base our IOPS needs we used some internet information and seems that everyone has different approaches.

So win7 will use non persistent desktops

microsoft office will be delivered via MS-Appv

Several Java apps will be delivered via MS-Appv

Our users WILL be using the VDIs 8 hours a day for 5 days a week

 

So we use the followng numbers (from several internet sources)

Win7 32 bit normal user (2gb ram, about 10GB disk, 1vcpu) = 12 IOPS (not calculating boot storms)

Number of VDI= 500

Storage needed= about 10GB per VDI for a total of 5000GB (5TB)

Write ratio=70%

Read ratio=30%

Raid levels used for calculations =RAID 10 (write penalty of 2)

Headroom = 30% of the final calculation

12 IOPS *500 users=6000 IOPS

30% headroom of 6000 IOPS=1800 iops

Total IOPS + headroom = 7800 IOPS

 

So I *think* need 7800 IOPS to support aceptable response times and latency times for 500 VDI. Since I cannot seem to find proper docs about IOPS on HP Lefthand products, I need to use the average IOPS of a SAS 6G disk which seems to be 180 IOPS/disk so I will need 7800/180=43 disks not taking into consideration controller cache and other magic the HP lefthand boxes can do.

 

According to this document: http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA3-4911ENW.pdf

And usgin the lowest value of an SSD with write cache off, I can get about 10K IOPS from an HP SSD.

 

So my questions will be:

1- If I only need a physical SSD to do that many IOPS (not that i will use only one, probably 4 on a raid 10) then what options can I have from HP to address this many iops needs instead of buying a 43 disk array?

2- Can I add SSD to a P4300?

3- Anyone here have IOPS values from Lefhand units at RAID10 in hardware and RAID5 in hardware?

 

Notes:

Someone recommended a HP MSA 2040 storage with SSDs on it. But this unit has only FC ports and all the investment is iSCSI. Any other HP products hopefully from Lefthand units than can support SSD and 5TB via ethernet/iscsi?

 

Looks like the P4900 might be my only option (part number QW932A).

http://h10010.www1.hp.com/wwpc/us/en/sm/WF06b/12169-304616-3930449-3930449-3930449-4118659-5219813-5...

 

 

Thanks,

 

sources:

HP MSA 2040 storage: http://h18006.www1.hp.com/storage/pdfs/4AA4-6608ENW.pdf

 

HP P4900 G2 SSD: http://h10010.www1.hp.com/wwpc/us/en/sm/WF06b/12169-304616-3930449-3930449-3930449-4118659-5219813-5...

 

IOPS for VDI workloads: http://www.slideshare.net/btdrew/iops-considerations-for-vdi-workloads

 

community link: http://h30499.www3.hp.com/t5/HP-StoreVirtual-HP-LeftHand/Maximum-IOPS-for-P4300/td-p/5414211#.UdNMX6...

 

 

 

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Honored Contributor
David_Schwartzs
Posts: 235
Registered: ‎05-13-2013
Message 2 of 7 (1,155 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

The P4900 is designed for this purpose - it has special SSD caching versus other StoreVirtual/Lefthand products designed to help prevent problems with boot storms. Plus, the blades would communicate with the SAN across the backplane, providing the best available bandwidth.

If you don't want to go bladed SAN, your best price/performance option, honestly, is probably to buy a pair of StoreVirtual 4730 nodes. The 4730 nodes have 25 SFF SAS drives. Part # B7E27A is the 25 x 600GB node.

One last question... are you intending to run 500 VDI instances on only 4 BL460c blades? At most, that's 64 cores of processing power assuming 8 x 8-core processors... I think that might be undersizing a bit unless your workloads are really, really, really light.
Regards,
--
David Schwartzstein
IT Channel Sales Expert / Solutions Architect

Currently looking for my next opportunity - http://www.linkedin.com/in/pctechyoda

If my post solves your problem, please kindly take a moment to mark my post as a solution. Thank you.
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Frequent Advisor
Erick Arturo Perez
Posts: 73
Registered: ‎02-28-2008
Message 3 of 7 (1,139 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

Hi David,
No, we are not planning to use those blades for VDI. I was just saying what we have. We have found on several documents on internet, that for our kind of load an average of 8 VDIs per core is somewhat normal (if Im wrong please feel free to point me in the right direction).

As for the SSD storage, I just came across this:
HP D2220sb Storage Blade with support for up to twelve 800GB or 400GB SAS 6G MLC SSD.
http://h18000.www1.hp.com/products/quickspecs/productbulletin.html#spectype=north_america&type=html&...

I'm thinking of a D2220sb with the twelve 800GB drives, format as RAID5 because with the performance I get I can spare the RAID penalty of 4 for a RAID5 array. And I get the VSA package so I can present the blade as an iSCSI target at 10Gbps. Will have to check on pricing and see if its within expectations.

That is the whole idea of a c7000 right? populate blades and reduce cabling and complexity.

 

your comments welcomed.

 

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Honored Contributor
David_Schwartzs
Posts: 235
Registered: ‎05-13-2013
Message 4 of 7 (1,137 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

The D2220sb blade option isn't a bad one - just keep in mind that, just as with physical Lefthand products, best practices would be to purchase two and run in Network RAID 10 mode (with RAID 5 locally) to protect you in case of failure of a server or storage blade.

As for how many cores you need, well, it would depend on how many simultaneous active users you believe you'll have, and what the CPU workload is. Hard for me to answer exactly.

The formula I personally use is this -
Number of users * percentage of users expected to be active users similtaneously * average percentage of CPU used by the applications on a normal desktop

Essentially, if I have 500 users, 100% similtaneous, 100% CPU core utilization on a normal desktop, then I'd need 500 cores. If I have 500 users, 50% similtaneous users, 50% CPU utilization, I only need 125 cores.

Hope that makes sense, hope this helps.
Regards,
--
David Schwartzstein
IT Channel Sales Expert / Solutions Architect

Currently looking for my next opportunity - http://www.linkedin.com/in/pctechyoda

If my post solves your problem, please kindly take a moment to mark my post as a solution. Thank you.
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Frequent Advisor
Erick Arturo Perez
Posts: 73
Registered: ‎02-28-2008
Message 5 of 7 (1,134 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

David, thanks again. Very good info on the cores thing.

 

To avoid reposting, I opened another post regarding the D2220sb and some questions about using it. I post it here since we are talking about it.

http://h30499.www3.hp.com/t5/Proliant-Storage-Systems/HP-D2220sb-with-VSA-software-next-to-4-node-Hy...

 

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HP Pro
HPstorageTom
Posts: 32
Registered: ‎01-31-2012
Message 6 of 7 (1,121 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

Erick,

 

you are neglecting any write raid penalty in your IOPS and disk number calculation. Having 12 IOPS 30/70 r/w will result into 12 x (0.3 + 0.7 *(NetWorkRAID penalty  * HardwareRAID penalty )) backend IOPS. So if you follow the general recommendation for VDI configurations to use Hardware RAID 10 then you would have:

 

   12 x (0.3 + 0.7 * (2 *2)) =  37.2 IOPS per users

 

And if you go then for 500 users, you will need 18600 IOPS.

 

Now, I have seen that the P4x00 systems with the LFF 15k disks can do approx. 220 IOPS/disk. So this would mean you need to have a cluster with 85 disks!

 

This is only an first estimation. If you are building VDI solutions, then the required storage configuration depends a lot on the VDI software stack you are using. Vendors like VMware, Citrix and now Microsoft with their Windows 2012 VDI solution stack do have some capabilities to hide some of the IOPS from the backend or to split some of their workload to different volumes.

 

 

 

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Frequent Advisor
Erick Arturo Perez
Posts: 73
Registered: ‎02-28-2008
Message 7 of 7 (1,073 Views)

Re: Using hp lefthand p4300 g2 for VDI sizing for IOPS not storage

Tom, I was not neglecting the write penalty. I just failed to post the complete calculations that we did. This can be for at least medium usage VDI. Plus we will usee a golden image with linked clones.

 

In terms of storage we are looking at the P4900 as David suggested. We are also looking at the MSA2040 (FC connectivity) both are SSD solutions however the MSA will need FC cards and other stuff in our c7000 which was built on iSCSI-based connectivity.

 

However thanks for pointing out your calculations for doing the math. This has been added to my excel sheet of calculations.

 

 

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