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Re: [Xen-users] Xen + SAN

On Fri, Jun 24, 2011 at 2:03 PM, Simon Hobson <linux@xxxxxxxxxxxxxxxx> wrote:
> Fajar A. Nugraha wrote:
>> If you need SAN for other purposes (e.g. live migration), then others
>> have already provided some good example. However, personally I'd check
>> again with the requirement. It's possible that the "best" setup for
>> you might be:
>> - a zfs-based storage appliance (e.g. napp-it, nexentastor) with lots
>> of disks (mirror), lots of memory, and SSD for L2ARC/SLOG to provide
>> high I/O throughput
>> - nfs and image-based disks to provide easy management
>> - tap:aio or tap:vhd on Xen side
> Do you have any feeling for how such a setup might compare, performance
> wise, with a local disk setup with the same disks and LVM and a partition
> per client block device ?

Local disk with block devices should definitely be faster.

But here's the catch: notice I specifically suggest zfs, lots of
memory, and SSD?
zfs/zvol by itself has lower performance compared to plain block
device. However it's also the only filesystem that I know of that can
use SSD to speed up both read and write. It's something that LVM/ext4
can't do. So it just might be able to offset performance penalty of
zfs + nfs + file-based-image.

... or if you have the money, simply buy EMC/Netapp-base/Oracle
storage with cache SSDs :D


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