Re: [Xen-users] iSCSI and LVM

[Serge Fonville <serge.fonville@xxxxxxxxx>]

Hi

>> I am going to get a storage server which will be connected to my Xen
>> hosts via iSCSI/Ethernet. I wish to use LVM for the DomU disks. The
>> storage server will have a RAID10 array, and 2 Xen hosts will connect
>> to this (Each will have a 50% share of the RAID10 array, space wise).
>>
>> What is the best way to go about this? Should I:
>>
>> a) Split the RAID10 array into 2 partition on the storage server, and
>> export 1 partition to each xen host, then let the Xen host manage LVM?
>>
>> or
>>
>> b) Do all LVM stuff on the storage server and export each LVM logical
>> volume to the correct Xen hosts via iSCSI? Since each host could have
>> around 100 VMs on it, that's a lot of iSCSI exporting!
>>
> If you export two "big luns" and do the LVM stuff on each Xens server
> you will not be able to "switch" a VM from one server to the other (with
> xm save/restore for example). With that setup a VM can only be started
> on a specific server. Also you will have two LVM sets to manage.
>
> If you do all the storage management on your SAN migrate a VM from one
> server to the other will be easy and even done "live". Also the storage
> management will be "unified". The only problem could be the maximum
> number of iSCSI Luns on yours SAN, but it often is greater than 127
> distinct units.
>
> Ok thanks for the advice. So I think I shall go down the root of doing all
> LVM stuff on the SAN.
>
> However, I think that I will need more than 127 virtual machines, so having
> an iSCSI target per VM is probably not an option. Is there any other
> solution for Ubuntu/Debian?

Would it be an option to have one iSCSI target, used by multiple
clients where only one clients accesses a directory at a time??
that way it would be way easier to mgrate a vm from one host to another.

HTH

Regards,

Serge Fonville

-- 
http://www.sergefonville.nl

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