I have a Primary/Secondary 2 nodes DRBD setting as shown
global { usage-count no; }
common { syncer { rate 4M; } }
resource r0 {
protocol B;
startup {
wfc-timeout 15;
degr-wfc-timeout 60;
}
net {
cram-hmac-alg sha1;
shared-secret "whateverblahblahblah";
max-buffers 4096;
max-epoch-size 4096;
}
handlers {
split-brain "/usr/lib/drbd/notify-split-brain.sh [email protected]";
}
on node01.chofert.com {
device /dev/drbd0;
disk /dev/sdb1;
address <public_IP_1>:7788;
meta-disk internal;
}
on node02.chofert.com {
device /dev/drbd0;
disk /dev/sdb1;
address <public_IP_2>:7788;
meta-disk internal;
}
}
I moved to Protocol B as nodes are in different networks and B it is enough for my needs. And rate limited to 4Mb as total bandwith between servers is 12Mb (low, I know, but writing is really really few bytes a day).
Trouble is, probably due to a nightly process which eats up CPU, DRBD crashes around 2 hours. After that, despite of quite low intense writing, at least 2 or 3 full partition re-syncs take place a day.
My question is: how DRBD works upon replication? I mean why do I see full partition re-syncs instead of just the few bytes written?
May just 1 sector of difference affect DRBD proper behavior?
PARTITION AT NODE1:
Disk /dev/sdb1: 8588 MB, 8588886528 bytes
255 heads, 63 sectors/track, 1044 cylinders, total 16775169 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
PARTITION AT NODE2
Disk /dev/sdb1: 8588 MB, 8588886016 bytes
64 heads, 32 sectors/track, 8191 cylinders, total 16775168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000