aschmitz at lehighgas.com
Fri Feb 20 11:13:22 CST 2009
> -----Original Message-----
> From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-
> bounces at dell.com] On Behalf Of Maxime Kurkdjian
> Sent: Friday, February 20, 2009 11:56 AM
> To: linux-poweredge at dell.com
> Subject: MD3000i
> I would like to setup a HA storage solution.
> I was thinking of this architecture:
> MD3000i with 2 controlers
> connected througt gigaEthernet iSCSI to
> 2x 2950III On Debian linux
> debian box delivering NFS to an other network
> 1/ can i "mount" in iscsi the same LUN on both 2950 ? so they will see
> the same data
You can connect to a single iSCSI LUN from both 2950s at the same time. However, unless you are using a cluster-aware filesystem, you probably should not try to mount the filesystem on both nodes at once. I think if you attempt this using ext2/3, etc the filesystems will step on each others toes and you'll end up with a corrupt filesystem.
> 2/ NFS HA will be acomplished by VRRP or other hot swap VIP address, so
> any R/W operation will be done by the standby server (newly active).
> this is an active/passive configuration.
That would probably work, again, as long as the iSCSI block device is only mounted (and NFS exported) from one server at a time. If you can set it up so that mounting/unmounting of the filesystem is part of the failover/failback process, you should be okay.
> same question with Mysql, but both MySQL instance will probably be
> running at the same moment (but the standby will not be used) to speed
> up the balancing in case of failure.
> is there any problem with that ?
Someone with more mysql experience than me might want to weigh in on this one, but I think you're probably better off using separate underlying block devices for this one and taking advantage of one of mysqls built in replication or clustering features. Again, I haven't actually proven it out on my own, but my sense tells me that mounting an fs with your mysql data from two servers at once using a non-cluster-aware filesystem will probably trash the filesystem. If I'm wrong, though, someone definitely let me know because it could save me some hassle in the future :).
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