Re: [Xen-users] Storage Resource RAID & Disk type

[Errol Neal <eneal@xxxxxxxxxxxxxxxxx>]

On Mon, 07/09/2012 04:52 PM, John Buchanan <John.Buchanan@xxxxxxxxxxxxxxxxxx> 
wrote:
> Are there any best practice recommendations on RAID & disk type for the 
> shared storage resource for a pool?  I'm adding shelves to a HP MSA2000 G2, 
> 24 drives total, minus hot spare(s).  I can use 600GB SAS drives (15k rpm), 
> 1TB or 2TB Midline SAS drives (7200rpm).  I need about 3TB usable for roughly 
> 30 VM guests, 100GB each, web servers so I/O needs are nominal.
> 
> I'm also going to need to get 4TB usable space for a SQL Server data volume 
> out of those 24 drives, unrelated to the VM boot volumes, hence my quandary.
> 
> If anyone has virtualized 20-30 VM web servers on a midline SAS or SATA based 
> storage resource I'd love to hear if performance was adequate.  Going that 
> route would easily meet my capacity requirements.
> 

Do you need all 30TB on the storage repo? One of the mistakes I commonly see 
people make is that they completely rely on shared storage for ALL non-OS 
related data. Can you leverage NAS protocols to reduce the amount of TB 
required for VMS? This way you can go with lower capacity, but higher 
performing drives. 

I'd also recommend that you diversify your storage pools and have some variety 
for different i/o types and sizes. For example, depending upon the profile of 
your database (data warehouse, transactional, etc), I'd isolate it on it's own 
distinct storage pool. 

Your I/O requirements are just that. If  you have 30x VMs of the same type, I'd 
review my avg read/write p/s and calculate that against the drive. Keep in mind 
that most Enterprise RAID controllers have some sort of hybrid storage 
technology now that allows you to use SSDS to accelerate reads and writes. If 
you travel a proven route in that city, then you can certainly go with the 
midline sas products so long as you have a few hot spares in the chassis and on 
hand. 

My two cents for whatever it's worth. 

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