[TriLUG] Disk subsystem recommendations

[Clay Stuckey]

The tricky thing is that there are several factors to disk  
performance. You have seek time (how much time it takes to find the  
data) then you have the read/write MB/s that is quoted. This is  
typically sequential read/writes. I expect you will have a mix of  
sequential and unordered read/writes in the real world.

While raid-0 does increase your transfer rate, you are still limited  
to a single spindle. This means your host OS and VM(s) will be  
fighting for head time. I have been running 3 fast sata drives in a  
raid0 for a while and have felt that I should have much better  
performance. That was until I realized that I can only get 1 piece of  
data at a time. I just recreated my volumes as 3 single drives. I have  
the host os on 1. The other 2 drives will each get a vm. I expect I  
will see a major performance increase for my situation.

If your host/guest machines are performing normal operations (ie: many  
small read/write operations), it would seem that seek time and  
separate spindles is what you need.

I don't know how solid state drives compare with platter drives. Maybe  
they can read/write more than one item at  a time.

I will let you know how my performance works out next week.

Clay



On Nov 25, 2009, at 4:36 PM, Ron Kelley wrote:

> x2 on the SSDs.  $489/ea for the Intel 160GB G2 SSDs  
> (zipzoomfly.com).  Put a pair in RAID-0 for $1K.  Very fast and  
> should last a long time.
>
> -Ron
>
>
>
> On Nov 25, 2009, at 4:31 PM, Joseph Tate wrote:
>
>> I don't think you want the overhead of LVM.  I'd stick with  
>> straight partitions.
>>
>> Why not go solid state disks?
>>
>> On Tue, Nov 24, 2009 at 10:02 PM, btncix btncix <btncix at gmail.com>  
>> wrote:
>>> I don't know much about VMWare nor much about virtualization, but  
>>> if your
>>> main concern is performance, I would suggest you keep RAID-0 and  
>>> create
>>> separate partitions. If you're worried about flexibility with hard  
>>> drive
>>> partitions, look into LVM for your root partitions and logical  
>>> partitions
>>> for your boot partitions. Of course, this more difficult to setup  
>>> than what
>>> you were thinking about, but it let's you keep RAID-0 and still  
>>> create your
>>> VMs with direct physical access to hard drive.
>>> --
>>> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
>>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>>>
>>
>>
>>
>> -- 
>> Joseph Tate
>> Personal e-mail: jtate AT dragonstrider DOT com
>> Web: http://www.dragonstrider.com
>> --
>> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>
> Thanks,
>
> -Ron
> rkelleyrtp at gmail.com
>
> --
> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions