[DRBD-user] Expanding a cluster

Lionel Sausin ls at numerigraphe.com
Fri Feb 1 11:10:08 CET 2013

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

Le 31/01/2013 18:27, Adam Goryachev a écrit :
> 1) Stop DRBD on secondary
> 2) Pull all drives on secondary
> 3) Add all drives on secondary and build new RAID6 array
> 4) Enable DRBD on secondary
> 5) sync from primary to secondary
I second that. Rebuilding 16 disks RAID6 is very long.
> Danger of read errors on the primary during this sync
Before you start, "drbdadm verify all" will make sure both nodes can 
actually read their disks.
Bonus: the resync will make sure the RAID can actually write to the 
disks (no bad surprise).
> (...)Finally, I think you have a fairly high risk with 16 drives in a single
No way. With DRBD it's like RAID6+1 and you still should have backups.
Losing 3 disks on both nodes at the same time means fire, lots of bad 
luck, or evil people being bad.
When it eventually happens, a downtime is probably OK - rebuild from 
scratch and restore backups.
By the way, moving one node to a building across the street protects 
from fire.
Lionel Sausin.

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