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IBM X3200 with LSI RAID, slow disk performance in Hyper-V virtual machine ?

Posted on 2009-12-21
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Last Modified: 2013-11-06
I have Ibm X3200, with RAID 1 on disk 1+2
Host OS (server 2008 with hyper-v) are installed on RAID disks.
VHD file are 60GB, and fixed size. In virtual machine are installed Server 2008.
Problem is that copy on virtual machine on same disk, from one folder to another folder is slow, only 5-6 MB/sec , but if copy from this disk to another disk than is ok speed (40-60 MB/sec).
I suspect that is problem in RAID controller because if VHD file is on disk that is not configured as RAID, speed is ok.
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Question by:tehnoline
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by:Maniac_47
ID: 26108948
What raid controller are you using?  Have you recently installed any updated drivers / firmware for this?  

Also, do the VMs have the RAID drivers required for this?
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Author Comment

by:tehnoline
ID: 26109170
RAid card areLSI 1064e, comes with server. All driver are up to date, FW also.
RAID drivers are not required in VMs because Host OS handle with drivers for all devices. Only Hyper-V integration services setup disk are necessary for VMs, AFAIK ? Wrong ?
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Maniac_47 earned 1500 total points
ID: 26109203
hmm,

It could be that its very slow for a few reasons:

1, the RAID controller might have a smaller cache and can't handle the I/O operations with this kind of setup.

2, Since you have 1 logical disk running RAID 1 (slower performance than other RAIDs like 5), and your VHD sits on this same disk, That would be the same as doing a file copy within the same volume - there is only 1 disk read/write head so copying data will be much slower as its running the machine and its processes and performing a copy, forcing a lot of I/O to a "single" disk (as far as hyper-v is concerned).
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Author Comment

by:tehnoline
ID: 26109241
1. Maybe, I will try if no other solution buy some advanced RAID controler with more cache.

2. I understand that is 1 read/write head and performance are /2 , but on host OS same test work with 40-50 MB/sec, in VMs are 5-6 MB/ sec , tooo slow, not slow, dramatically slow.
Another thing are that if I copy VHD to disk which is not configured in RAID,  performance on Host OS, and VMs, are same, maybe 2-3 MB/sec up/down.

3. I will try for test Stripping RAID, and install Host OS, and do test.
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Author Comment

by:tehnoline
ID: 26109253
I'm try install Host OS on single disk, no RAID array configured, and on same disk put VHD (same situation like in real setup), only difference are NO RAID array, and performance are quite OK !
 
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by:Maniac_47
ID: 26109296
I agree with you, I was just giving a reason why this could be.

Your RAID controller may have a smaller cache than the operations you are asking it to complete require.  Also, RAID1 is a lot of overhead for many I/O operations, which a Virtual Machine does a ton of every second.  With so much going on, it may impact the performance.

I'd be curious if you could get yourself a cheap / higher cache RAID controller and perhaps run with a different RAID setup (i.e. VHD on different disk than Host on a single-stand alone- disk).

I suspect its hardware related and not the configuration as you've stated that you have updated your drivers/firmware on the host, and it seems you know enough about the software/hyper-v side to rule out any issues.  

I don't know if its related, but the only other thing I could find was this relating to hyper-v:

Did you install the Hyper-V RTM bits before adding the Hyper-V role? (KB950050)
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by:Maniac_47
ID: 26109304
EDIT:

I would consult with another expert before buying anything relating to this.  My experience has been with only several similar systems and I'm curious if there are any other Win2k8 Hyper-V experts out there that agree or disagree with my assessment of the situation here.  I believe I've answered your question as best I can at the moment, and if you need anything else, please let me know.
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Author Comment

by:tehnoline
ID: 26109381
For this: "Did you install the Hyper-V RTM bits before adding the Hyper-V role? (KB950050)"

My answer are: I'm not sure that I install this update because Hyper-V are in production close 1 year, but I have 2-3 VMs, and second VMs have all disk assigned for self (RAW access), because this VMs are File server, and works ok.
SQL server are on VM that are on VHD and I experience slow performance and go on testing.
But I have second server IBM X3200 same product number, and for test I install Server 2008 R2 which are not affected with this update, and test performance are same like Server 2008.

I wait for another your or someone opinion before buy anything, and I send mail to IBM service for opinion.
Thanks !
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by:Maniac_47
ID: 26109385
Thank you, please don't forget to assign points if I've help you!
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Author Comment

by:tehnoline
ID: 26113807
Today I've tryed enable Write Cache, and performance are much better.
My question are: should I turn Write Cache on, because RAID controller have no Battery backup, and if any unexpected restart happen I risk that system corrupt ?
How much is that risk or is not that bad that I must buy RAID with more Cache and/or Battery, and what is major Cache or Battery (I know more Cache + battery are awesome but too expensive) ?

Thanks
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by:Maniac_47
ID: 26114371
how much power does your server need?  you could buy a very basic battery backup for less than $250.  That way you could do both.

Would you like me to post some quotes for those (sample quotes of Battery backups that you can get cheap and will work very well)?
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Author Comment

by:tehnoline
ID: 26115213
How much power ? What power ?
Post quotes please !
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by:Maniac_47
ID: 26115619
Smart UPS 1500: (provides PowerChute, used to protect the system by offering shutdowns after an extended power outage - automatic restart when power is restored and alarms/alerts)

http://www.google.com/products/catalog?hl=en&q=Smart+Ups+1500&cid=11099740360386480703&sa=title#p

APC Back-UPS XS 900 (I currently have 2 servers attached to 2 of these):

http://www.google.com/products/catalog?q=APC+UPS+900&hl=en&cid=2896123199560703257&sa=title#p

APC Back-UPS 1500:

http://www.google.com/products/catalog?q=apc+back-ups+xs+1500&hl=en&cid=8442150114904046104&sa=title#p

I'm just listing APC as an example, there are many other affordable options out there like Tripp-lite that can offer the same protection for all about the same amount.
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Author Comment

by:tehnoline
ID: 26115636
Friend :) , with Battery i think on RAID controller battery, no UPS.
I have UPS, but this is not RAID battery !!
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Author Comment

by:tehnoline
ID: 26115646
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by:Maniac_47
ID: 26115649
"have no Battery backup," ~ you

I thought you were saying [the server] with the raid controller doesn't have a battery backup.  I think I mis-understood you.
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Author Comment

by:tehnoline
ID: 26115661
yes, I think on RAID Battery backup, server without UPS, no thanks :)
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Author Comment

by:tehnoline
ID: 26115670
my text: "because RAID controller have no Battery backup" , i think RAID Controller without battery, no server....mis-understood happens :)
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by:Maniac_47
ID: 26115673
Yea, I wouldn't enable write caching on a raid setup without a raid battery backup.

You *could* if you feel like you have strong backups and viable snapshots to recover to, but it would be throwing all your eggs in the basket of trusting your backups are flawless.
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Author Closing Comment

by:tehnoline
ID: 31668734
Small Cache are reason for slow disk write on virtual machine.
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