Hi Tommy,

I understand that sending a single raw device from the SAN to the DomU would eliminate an extra layer of ZFS and hence provide a performance boost but, if I understand you correctly, it would also eliminate the redundancy my SAN delivers while also bounding my ability to grow /export/home over time.

Specifically, my SAN has 24 SATA drives, which are in RAIDz2 - i.e. 4x(4+2) - a good balance between MTTDL and IOPS. If a take out 3 drives to give to the DomU to use for its LUNs, with a zpool with matched redundancy, I think I would be left with a less performant Dom0 zpool (having taken out a stripe) and a difficult to grow DomU zpool (as I couldn't simply allocate more from the SAN). That doesn't sound like it justifies giving /export/home a small boost in performance...

I'm still somewhat new to storage, so please tell me if I'm missing something

Thanks again,
Kent


On 1/26/10 11:26 PM, Tommy McNeely wrote:
ZFS is the best approach, but I agree with Mark, it would be best to send the 
domU a *raw* device (target) from the SAN, rather than a zvol if possible.

I have several other ideas about the "shared" home directories, but totally 
understand where you are coming from with all the firewall complex stuff, so I will let 
that be. When I used zones, I had one /export/home per physical server, with xVM I have 
one per virtual machine in my firewall complex, and I haven't sorted out what I want to 
do there yet.

Good luck!
Tommy

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