<div dir="ltr"><div><div>I've had zero issues using client quorum (cluster.quorum-type<br></div>=auto) and three nodes/bricks. Testing using node shutdown and node kills.<br><br></div>I'd really recommend going with three nodes - maybe one as a arbiter volume if disk space is an issue.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On 29 October 2015 at 03:52, Alan Hodgson <span dir="ltr"><<a href="mailto:ahodgson@simkin.ca" target="_blank">ahodgson@simkin.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I have a couple of 2-node clusters I'm hoping to move from drbd+ocfs2 to<br>
glusterfs. I've been testing with 3.7.4 and I have a few questions.<br>
<br>
1) I gather that 2-node replicas have quorum issues, and if you disable<br>
quorum, then they have split-brain issues. Do split-brains happen even if the<br>
network link is very reliable - I have point-to-point 10Gbit, and the only<br>
clients will be the brick servers? If so would it make more sense to make this<br>
a 4-node cluster and use arbiter volumes?<br>
<br>
2) Sharding looks pretty good, as the volumes will be used exclusively for<br>
large VM backing images. I've been testing with 1GB shard sizes and<br>
performance seems good. It seems that sharded volumes don't support discard,<br>
though (ie. fstrim within VM guests). Is there a timeline on when that might<br>
be implemented?. Discard seems to work right on non-sharded volumes, but then<br>
heal times seem like they'll be an issue.<br>
<br>
3) Is there operational documentation for maintenance procedures, like how to<br>
properly shut down nodes in a way that won't impact clients? What I got from<br>
a recent mailing list post suggests something like:<br>
<br>
killall glusterfs<br>
killall glusterfsd<br>
systemctl stop glusterd<br>
<br>
That seems to work in testing, the client VM's stay responsive. Is it safe?<br>
<br>
Thanks in advance for any advice.<br>
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</blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature">Lindsay</div>
</div>