Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello everyone. I have a fairly simple 2-node CentOS 7 setup running KVM virtual machines, with DRBD 8.4.9 between them. There is one DRBD resource per VM, with at least 1 volume each, totalling 47 volumes. There's no clustering or heartbeat or other complexity. DRBD has it's own Gig-E interface to sync over. 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. 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. 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. Almost every night, it reports at least 1 volume which is out-of-sync, and I'm trying to understand why that would be. 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. Any suggestions what might be going on here? Thanks. Luke Pascoe