[Linux-cluster] GFS, iSCSI, multipaths and RAID

[Alex Kompel]

On Mon, May 19, 2008 at 2:15 PM, Michael O'Sullivan
<michael.osullivan at auckland.ac.nz> wrote:
> Thanks for your response Wendy. Please see a diagram of the system at
> http://www.ndsg.net.nz/ndsg_cluster.jpg/view (or
> http://www.ndsg.net.nz/ndsg_cluster.jpg/image_view_fullscreen for the
> fullscreen view) that (I hope) explains the setup. We are not using FC as we
> are building the SAN with commodity components (the total cost of the system
> was less than NZ $9000). The SAN is designed to hold files for staff and
> students in our department, I'm not sure exactly what applications will use
> the GFS. We are using iscsi-target software although we may upgrade to using
> firmware in the future. We have used CLVM on top of software RAID, I agree
> there are many levels to this system, but I couldn't find the necessary is
> hardware/software to implement this in a simpler way. I am hoping the list
> may be helpful here.
>

So what do you want to get out of this configuration? iSCSI SAN, GFS
cluster or both? I don't see any reason for 2 additional servers
running GFS on top of iSCSI SAN.

If you need iSCSI SAN with iscsi-target then there are number of
articles on how to set it up. For example:
http://www.pcpro.co.uk/realworld/82284/san-on-the-cheap/page1.html Or
just google for iscsi-target drdb and heartbeat.

If you need GFS then you can run it on the storage servers (there is
no need for iSCSI in between).

If you need both then it can get tricky but you can try splitting your
raid arrays in a way that half is used by GFS cluster and half is for
DRDB volumes with iSCSI luns on top and RedHat Cluster acting as a
heartbeat for failover (provided you can also do regular failover with
GFS running on the same cluster - I have never tried it before).

-Alex