VM Ware SAN - HD Performance

[mattx]

Does anyone have experience on running virtual servers on a SAN [ Hitachi SMS-100 ] http://www.hds.com/uk/products/storage-systems/simple-modular-storage.html in which the HDs are NOT 15,000 RPM ? Is there a difference in performance on slower speed HDs ? Edited March 26, 2010 by mattx

[danrhodes]

Yes there will be a difference, normaly you would run the OS Drive on the local storage of the server and then have the data drive of the server on the SAN.

[Duke]

Kind of...

 

I have a Sun 7410 that uses 7.2k SATA drives for the primary storage, but also has Flash SSDs to get good IOPS. I also have a NetApp FAS2020 with just 7.2k SATA drives and ran the odd virtual machine off there with no issues.

 

It will work, but if you have disk-intensive applications on the VMs then it won't be as fast as 15k disks or SSDs. If you can work out what IOPS you need then estimate the performance of the SAN (spindles / disks / IOPS per disk) that'd be a good start.

 

What's the price on the Hitachi - have you looked at any alternatives?

 

Chris

[mattx]

Yes there will be a difference, normaly you would run the OS Drive on the local storage of the server and then have the data drive of the server on the SAN.

 

I thought the best pratice was to hold the virtual OS's on the SAN [ as long as you have a dedicated ISCSI or Fibre connection ] ?

[ful56_uk]

We run sas and sata sms 100 without any problems. sas is used for servers virtual drives and sata is for data store both using iscsi

[Duke]

I thought the best pratice was to hold the virtual OS's on the SAN [ as long as you have a dedicated ISCSI or Fibre connection ] ?

 

Yeah, that's what I do. I think (may be wrong) danrhodes was talking about a physical server rather than a VM. e.g. a standard server install with a mapped data drive on a SAN.

[webman]

What disks are in your SMS100, mattx? We were advised not to run VMs directly off our SATA SMS100 due to 1) SATA and 2) RAID6 performance.

[danrhodes]

I was advised by techies at Fujitsu that when running Hyper-V and Virtual Servers to have the Virtual OS disk on the physical servers local disk's and to have the data disk of the virual server on the SAN wether its iSCSI or Fibre attached. That was using DX80 or DX90 with fibre channel.

[mattx]

What disks are in your SMS100, mattx? We were advised not to run VMs directly off our SATA SMS100 due to 1) SATA and 2) RAID6 performance.

 

Have not got it yet !! Still trying to work out the best approach - I don't suppose they provided you examples of the performance problems with RAID6 & SATA ?

[Theblacksheep]

HP iSCSI SANs here, VMware vSphere.... quite a difference in copy speeds to 1tb 7.5k disks and the 450gb 15k disks.

 

I use the 7.5k disks for VDI, ISOs and disk backups and non essential servers. All important server live on the fast disks.

[mattx]

Thanks to all regarding the disk speed which clearly indicates to me that 15,000 is the way to go - my only concern now is the RAID6 & SATA drives.

[tmcd35]

At my last place I built a iSCSI SAN around a SATA RAID-50 DAS box. I think the biggest performance hit was probably the SCSI connection between the server and the DAS. It's served a 1800 pupil split sight school (20+ VMWare servers) reasonably well for the past 2 years.

 

I hear they have recently bought a new iSCSI SAN based around 15k SAS RAID-50 DAS box, the DAS attaches to the iSCSI server via a 4-channel SAS link. I'm told the speed difference is amazing (unsurprsingly).

 

I'm building a NAS (rather than SAN) here. I'm going for 16 (i think) 15k 450Gb SAS drives in RAID-50 .

 

 

EDIT:

Thanks to all regarding the disk speed which clearly indicates to me that 15,000 is the way to go - my only concern now is the RAID6 & SATA drives.

 

You can get 15k SATA drives?

 

RAID-6'll be fine. I've used RAID-50, which is very similar and ever so slightly faster, with out any problems in the past. Personally though I'd go RAID-50 than RAID-6 for that slight performance boost.

Edited March 26, 2010 by tmcd35

[webman]

@mattx: Ah right We decided to go for the Sun 7110 in the end for VMs. Full RAID flexibility on SAS disks, with the options of NFS or iSCSI for connectivity. But no, no examples of the SMS100 performance. The web seems very lacking in tests for that SAN.

 

The SMS100 is purely data storage for our user/shared areas and SIMS for physical servers.

[mattx]

@mattx: Ah right We decided to go for the Sun 7110 in the end for VMs. Full RAID flexibility on SAS disks, with the options of NFS or iSCSI for connectivity.

 

The SMS100 is purely data storage for our user/shared areas and SIMS for physical servers.

 

That's the way it's looking for me - the SMS100 for data only. I suppose what I could do is get a meaty server with some large local HDs and run the hyper visor and a few VMs of that until we can get a better SAN. Need to save some money !!

I know it's putting all your eggs in one basket but I would run our PDC as a stand alone server still and move 3 other physical severs over as VMs......

Now need to think along the lines of backups.....

Edited March 26, 2010 by mattx

[webman]

That's the way we started. 2x Dell servers acting as VM hosts with the same disk types. If one server failed, in theory, we would transfer the disks from the failed server to the working one and just start up the VMs. But with a SAN this becomes much more efficient, fault-tolerant and quicker.

 

The Sun storage servers are very capable devices.

[K.C.Leblanc]

That's the way it's looking for me - the SMS100 for data only. I suppose what I could do is get a meaty server with some large local HDs and run the hyper visor and a few VMs of that until we can get a better SAN. Need to save some money !!

I know it's putting all your eggs in one basket but I would run our PDC as a stand alone server still and move 3 other physical severs over as VMs......

Now need to think along the lines of backups.....

 

You do relise that the hard drives aren't officialy user replacable on the SMS100. If you have a drive failure they advance swap the whole unit and you have to copy your data over.

 

If you're planning on keeping it when it goes out of warranty this could be a major issue.

[Duke]

mattx - Have you looked at the Sun storage stuff at all? Not sure how it compares to Hitachi on price, but mmm, so nice.

[danrhodes]

Have you considered the Fujitsu Eternus range? Cheap and very good boxes.

 

D

[DMcCoy]

I was advised by techies at Fujitsu that when running Hyper-V and Virtual Servers to have the Virtual OS disk on the physical servers local disk's and to have the data disk of the virual server on the SAN wether its iSCSI or Fibre attached. That was using DX80 or DX90 with fibre channel.

 

Doesn't this stop hot migration, one of the major benefits of virtualisation? I'd suggest that Fujitsu are simply wrong with this advice.

[mattx]

You do relise that the hard drives aren't officialy user replacable on the SMS100. If you have a drive failure they advance swap the whole unit and you have to copy your data over.

 

If you're planning on keeping it when it goes out of warranty this could be a major issue.

 

Yes I am aware of that but as this is [ now looking at it the SMS100 ] will be just for data and not VMs I can't see that being a problem.

[danrhodes]

Doesn't this stop hot migration, one of the major benefits of virtualisation? I'd suggest that Fujitsu are simply wrong with this advice.

 

Yep fair point, looks like I stand corrected. Can't run vmotion with the OS VDisk on the dead server!

 

D

[webman]

@K.C.Leblanc The SMS100 has two "repair slots" in which you insert new disks to replace the internal failed ones. After two failures, yes the whole box is replicated to another one.

[danrhodes]

@K.C.Leblanc The SMS100 has two "repair slots" in which you insert new disks to replace the internal failed ones. After two failures, yes the whole box is replicated to another one.

 

Were these repair slots an after though me thinks to meet the needs of the end users asking for them!

[apaton]

I was advised by techies at Fujitsu that when running Hyper-V and Virtual Servers to have the Virtual OS disk on the physical servers local disk's and to have the data disk of the virual server on the SAN wether its iSCSI or Fibre attached. That was using DX80 or DX90 with fibre channel.

 

I would disagree with this advice from Fujitsu if you want to use technologies like Live Migration (Hyper-V) or vMotion (VMware).

 

Live Migration or vMotion must have OS and Data LUN's on external shared storage(SAN).

 

Andy

[mattx]

mattx - Have you looked at the Sun storage stuff at all? Not sure how it compares to Hitachi on price, but mmm, so nice.

 

I shall be looking now - I think I have it in my head sort of the best way of doing this and it will have to be a 2 stage process.

 

At the moment I have 5 servers

4 of them are 2003 and 1 is a LAMP server

 

I think what would be the best bet will be to keep my main domain controller [ which has a ULT920 tape drive in ] and purchase a meaty beast in which I can move the other servers over to. [ P to V ] & hold those locally on a RAID1 or RAID5

The SMS100 will just be for data and when more money is on the table get a better SAN move the VMs over to and run.

Anyone else done something similar ?