<div dir="ltr">Hello everyone.<div><br></div><div>I have a fairly simple 2-node CentOS 7 setup running KVM virtual machines, with DRBD 8.4.9 between them.</div><div><br></div><div>There is one DRBD resource per VM, with at least 1 volume each, totalling 47 volumes.</div><div><br></div><div>There's no clustering or heartbeat or other complexity. DRBD has it's own Gig-E interface to sync over.</div><div><br></div><div>I recently migrated a host between nodes and it crashed. During diagnostics I did a verification on the drbd volume for the host and found that it had _a lot_ of out of sync blocks.</div><div><br></div><div>This led me to run a verification on all volumes, and while I didn't find any other volumes with large numbers of out of sync blocks, there were several with a few. I have disconnected and reconnected all these volumes, to force them to resync.</div><div><br></div><div>I have now set up a nightly cron which will verify as many volumes as it can in a 2 hour window, this means I get through the whole lot in about a week.</div><div><br></div><div>Almost every night, it reports at least 1 volume which is out-of-sync, and I'm trying to understand why that would be.</div><div><br></div><div>I did some research and the only likely candidate I could find was related to TCP checksum offloading on the NICs, which I have now disabled, but it has made no difference.</div><div><br></div><div>Any suggestions what might be going on here?</div><div><br></div><div>Thanks.<br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><p style="font-family:verdana,sans-serif"><span style="font-weight:bold">Luke Pasc</span><span style="font-weight:bold">oe</span></p><p style="font-family:verdana,sans-serif"><img src="http://osnz.co.nz/logo_blue_80.png" width="96" height="28"><font size="1"><br><b><br>
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