Re: [Xen-users] Network Storage

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Thu, Jan 22, 2009 at 1:50 AM, lists@xxxxxxxxxxxx <lists@xxxxxxxxxxxx> wrote:
>> treat xen domUs like any other physical server. You allocate a
>> different LUNs for each domU.

> Do you mean something like having a SCSI chassis attached to the VM server, 
> then exporting LUNs to each guest?

No. What I mean is :
- having a SAN/NAS that has direct access to disks
- having the SAN export LUNs to dom0. One LUN for each domU
- dom0s connected to SAN via either FC or iscsi
- have all dom0s import all domU's LUNs

>
>> In the end we find
>> that local storage actually provides MUCH higher I/O throughput, since
>> it has "dedicated" disks with plenty of I/O bandwitdh :p
>
> Ok, so you are just talking about local storage for the VM server, not so 
> much the individual guests.

Actually my point is if your primary concern is performance, it maybe
useful to simply use local disks instead of SAN. You'll lose live
migration abilites, but depending on the situation, it might be
useful.

>
>> As a side note, if you're already familiar with FC filers, you might
>> want to try SUN's new Unified Storage
>
> We're just a small house and don't have a big budget, especially in this 
> economy.
> That said, I have put together some pretty good hardware. I use a couple of 
> smaller BlueArc filers to export NFS/CIFS shares and have a couple of BlueArc 
> TITAN filers for when I need very fast I/O.
> I am also experimenting with building my own storage devices at this point. 
> For example, I've just put together a CentOS server with 4TB of storage using 
> parted and will be looking for leads on how to optimize I/O from such a 
> machine which will do nothing but server NFS shares.

You might want to try experimenting to share iscsi from that server as
well. iscsi can outperform NFS for certain requirements (for example:
domU's storage). Once you're familiar with using iscsi, then you can
try using opensolaris which AFAIK should make some jobs easier. SUN's
fishwork storage is based on opensolaris, but it has performance
enhancements (for example, the use of SSD) and a nice GUI.

Regards,

Fajar

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