Re: [Xen-users] Xen and iSCSI

[Ralph Passgang <ralph@xxxxxxxxxxxxx>]

Am Mittwoch, 15. Februar 2006 17:32 schrieb Michael Paesold:
> Javier Guerra wrote:
> > i think a better use of the resources would be:
> >
> > - two storage servers
> > - on each storage server:
> > ~ md raid to join all disks on one volume
> > ~ export volume with gnbd
> > ~ drbd to 'mirror' both volumes, making it HA

I had a very well setup that looked like:

Server1: Physical Disk / DRBD / LVM / GNBD
                                    | HA |                      
Server2: Physical Disk / DRBD / LVM / GNBD

connected via a gbit switch to 2 xen hosts.

I used LVM on the "SAN"-Hosts to have single volumes that I can export to both 
xenhosts for every vm. Both xenhost could access the gnbd device at same (but 
ofcourse I just used a normal filesystem for the vm's this wouldn't be a good 
idea). But that makes live migration possible (and working well with such a 
setup).

The DRBD devices are fault-tolerant because of heartbeat. It worked perfectly 
even if the active san hosts was switched off between a live migration of a 
vm from on xenhost to the other...

On the next (most likely production) setup I will use multiple disk in each 
san server (to have better performance) and I think then the setup will look 
like:

Physical Disk / RAID0 (Stripes) / DRBD / LVM / GNBD

-Ralph

> Using gnbd over drbd sounds cool. Do you or does anyone else have a
> heartbeat resource script for gnbd (to be used with drbd)?

no, only the normal drbd files but they are working very well (as long as gnbd 
itself is not the problem, and I never had problems with gnbd within my 
tests). 

> Best Regards,
> Michael Paesold
>
>
>
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