[Linux-cluster] wishing to run GFS on iSCSI with redundancy

[Rohit Grover]

Hello,

Thanks a lot for responding.

Ok, couple of notes:
>
> * MD is only unsafe in a cluster if it's used on multiple cluster nodes.
> That is, it should be fairly easy to implement a resource agent which
> assembles MD devices from network block devices - on one node at a time.



True. I would like to have MD assembling iSCSI initiators (the same set, of
course) at multiple nodes. This will facilitate load distribution.
Isn't it true that if MD is made to not cache any data flowing through it
(and leave GFS to do caching and coherency control across the cluster), then
MD should be a viable solution to putting together iSCSI initiators with
RAID?


* DRBD only will work with two writers (if 0.8.x+).  I'm not sure how many
> mirror targets you can maintain.


Could you please elaborate on this? I don't understand what is meant by
'DRBD will only work with two writers'. Thanks.


* Aren't most iSCSI targets RAID arrays already (?)


Yes, they are in our case. But we also want to survive software/firmware
failures of the iSCSI targets.


Thanks,
Rohit Grover.
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