On Fri, Jun 29, 2007 at 10:49:35AM +1200, Rohit Grover wrote: > 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. I think drbd only supports two-node mirrors. I.e., you can set up a mirror from only two nodes at a time, and that's it: no other nodes can access the data (directly, at least). I'm not sure how many sets of these mirror setups you can run on a given pair of nodes, or if there is even a maximum. > * 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. > Complexity has its own problems :) -- Lon Hohberger - Software Engineer - Red Hat, Inc. -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
