We're considering implementing gluster for a genomics cluster, and it
seems to have some theoretical advantages that so far seem to have
been borne out in some limited testing, mod some odd problems with an
inability to delete dir trees.  I'm about to test with the latest beta
that was promised to clear up these bugs, but as I'm doing that,
answers to these Qs would be appraciated...

- what happens in a distributed system if a node goes down?  Does the
rest of the system keep working with the files on that brick
unavailable until it comes back or is the filesystem corrupted?  In my
testing, it seemed that the system indeed kept working and added files
to the remaining systems, but that files that were hashed to the
failed volume were unavailable (of course).

- is there a head node?  the system is distributed but you're mounting
a specific node for the glusterfs mount - if that node goes down, is
the whole filesystem hosed or is that node reference really a group
reference and the gluster filesystem continues with the loss of that
node's files?  ie can any gluster node replace a mountpoint node and
does that happen transparently? (I haven't tested this).

- can you intermix distributed and mirrored volumes?  This is of
particular interest since some of our users want to have replicated
data and some don't care.

Many thanks
hjm
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Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine
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