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Re: R: [Xen-users] XCP and Openfiler as the storage


thanks for your answer, however that raised another question.

I have several hypervisors, which means if I create one big LUN, I will need different servers to have access to the same LUN and as far as I know iSCSI LUNs are not supposed to be shared. Obviously, within that same LUN, each hypervisor would be accessing different Logical Volumes, but in case a new LV or a new snapshot is created, it would have to allocate space from the LUN and that could lead to a scenario where the other hypervisors do not see the new LV or the new snapshot.

Have you encountered this kind of problem, or do you have a different scenario (perhaps only one hypervisor for the big LUN for example)?

Best regards,

On Apr 5, 2011, at 1:24 PM, <cluster@xxxxxxxx> <cluster@xxxxxxxx> wrote:

Hi Eduardo,

I am using this scenario (openfiler + XCP) from more than 1 year. I have had no performance loss but my openfiler is patched for using fibrechannel.

I suggest you to create only a big LUN (less than 2TB remember) and let XCP
manage it.

Best regards,

-----Messaggio originale-----
Da: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] Per conto di Eduardo Bragatto
Inviato: sabato 2 aprile 2011 16:46
A: xen-users
Oggetto: [Xen-users] XCP and Openfiler as the storage


I have been using Xen under CentOS and Openfiler as the storage for a while now, however with the release of RHEL6 without support for Xen and with the release of XCP 1.0, I have the impression it's time to move away from CentOS
and give XCP a try.

My greatest doubt is about LVM. Openfiler handles an entire RAID10 volume which is exported as smaller volumes created through LVM via iSCSI. However,
XCP also uses LVM to manage snapshots and such.

I believe if I start using XCP with my current storage server (Openfiler), I will end up with two layers of LVM -- first a volume on Openfiler which is exported via iSCSI, and then a new LVM layer created on top of the LUN I
will import via iSCSI on XCP.

How bad (performance-wise) would be to have two layers of LVM? Would it be too complicated to maintain? (I imagine it would be as simple as dealing with the same thing twice, but there's also XCP handling LVM, so I'm not
sure how that would work out).

Does anyone here has similar experiences they can share?

I know Openfiler does not have an API for integration with other appliances, so I believe XCP would not be able to create and manipulate the LVM directly on the Openfiler storage in order to avoid the two layers on top of each other. Does anyone if that kind of integration is doable, or even possible?

Best regards,
Eduardo Bragatto

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