[DRBD-user] What causes nodes to become out-of-sync?

Jeffrey Froman drbd.tcijf at olympus.net
Wed Jul 16 19:11:41 CEST 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I have a drbd resource performing replication for a block device on a 
pair of machines (not clustered), and it works wonderfully. Each 
evening, we run a cron job that does:

    drbdadm verify resourceName

Every once in a while, "verify" finds a few out-of-sync blocks, and we 
manually invoke a re-synchronization when this happens. All good.

My question is: what are the sorts of things that might be causing 
blocks to become out-of-sync on this resource? As far as we know, no 
changes are made or fiddling done on the nodes at any time.

Again, verification and re-synchronization works fine -- I'm just 
trying to get a feel for why these operations are required 

Thank you,

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