Reinhard Brandstaedter wrote:
> On Fri, 2007-01-19 at 11:18 -0200, Christopher G. Stach II wrote:
>> You have a few basic choices:
>>
>> 1. Export a single LV from dom0 as a full disk, allowing your domU to
>> see the LV as an entire disk and use partition tables.
>> 2. Export each single LV from dom0 as partitions, allowing your domU
> to
>> only see those partitions.
>> 3. Export the VG device from dom0, allowing your domUs to see all LVs.
>>
>> Since you're using a SAN, you may be aiming to support multiple Xen
>> boxes on the same device(s). If so, you're probably going to want to
>> run CLVM. The question is, "Where?" If you use #1 or #2, your dom0s
>> will have to participate in the cluster. If you use #3, you push the
>> clustering to the domUs (where I think it belongs.) #3 is less
> secure,
>> however.
>
> That's exactly what I want to do - booting several VMs from one
> read-only rootfs (one LV). But I think I will run CLVM on the Dom0s and
> use method #2. I haven't used CLVM yet, but I think it's easier to
> configure it on 2-3 Dom0s than on every DomU?
It's "easier" (if you've done it more than once, it's not that
difficult, but the first time...) if you run it on fewer dom0s, but it
also puts all of the VMs at risk of going down if your dom0 gets fenced
and reset. It also puts greater load on the dom0s, which could impact
VM performance quite a bit (like if you're using default SEDF params.)
You _could_ also use LVM in the dom0s without the cluster capabilities,
but you won't see any LV changes across the cluster until you reset the
machine(s). As with all of the other cluster suite stuff, there's also
the risk of it exploding in your face. :)
--
Christopher G. Stach II
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