Re: [Xen-users] High Number of VMs

[Christian Motschke <christian@xxxxxxxxxxx>]

I forgot to include the list…

Am 10.09.2011 um 09:18 schrieb James Harper:

>> Am 10.09.2011 um 02:23 schrieb "James Harper"
> <james.harper@xxxxxxxxxxxxxxxx>:
>> 
>>>> You don't actually need cLVM to do this!  All the
>>>> cluster infra does (for its nasty administrative overhead) is keep
> the
>>>> LVM metadata (not your actual data) consistent through cluster-wide
>>>> locks.  You can manage yourself by, for example, making changes on
> one
>>>> node and refreshing the other nodes with things like 'vgscan -ay'.
> I
>>>> typically allocate LUNs 500GB at a time.  You can invent means of
>>>> keeping things consistent that work for your environment, just test
> them
>>>> first.
>>> 
>>> Another thing cLVM does is enforce the restriction on snapshots.
> Without
>> cLVM you could create a snapshot on one node and completely trash the
> volume.
>> I believe the CoW action of LVM snapshots involves a metadata update
> so you
>> can't use it in a clustered environment. This is why I use LVM on the
> SAN
>> rather than on the DomU.
>>> 
>> That is no longer true. CLVM supports clustered snapshots. I use it
> already.
>> But there is another limitation. You have to open the LV in exclusive
> mode
>> (lvchange -aey). It is enough to compile CLVM with openais and you
> have your
>> Cluster running in minutes.
>> 
> 
> That's great news! I was checking the web every so often to see if this
> feature had been added yet but hadn't recently.
> 
If you use Debian, I can send a link where you can download my packages.

> Thanks
> 
> James

Christian
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