DRBD
(New page: DRBD handles the disk stuff. It's kinda like raid1 but over a network. Sometimes the nodes may refuse to connect. If this happens, check 'dmesg' for the message drbd1: Split-Brain det...) |
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[[User:Jdhutchin@ugcs.caltech.edu|Jdhutchin@ugcs.caltech.edu]] 22:08, 7 June 2008 (PDT) | [[User:Jdhutchin@ugcs.caltech.edu|Jdhutchin@ugcs.caltech.edu]] 22:08, 7 June 2008 (PDT) | ||
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Revision as of 07:18, 10 June 2008
DRBD handles the disk stuff. It's kinda like raid1 but over a network.
Sometimes the nodes may refuse to connect. If this happens, check 'dmesg' for the message
drbd1: Split-Brain detected, dropping connection!
This means that at some point, both of them thought they were primary. This can cause possible FS corruption, so drbd says that a human has to do something about it. The best thing to do is to run
drbdadm invalidate <resource>
on the host that doesn't have the data you want (usually the backup one). You will then be able to re-connect the nodes, and they will resync.
If the drbd connection is on the same link that the heartbeat is, you will always have a split-brain when the network cable is pulled. This is why we have automatic split-brain recovery enabled- the one that was most recently primary is the one that is considered authoritative. You can specify this with
net {
after-sb-0pri discard-older-primary;
after-sb-1pri consensus;
}
in drbd.conf
After you change a config file, you can update the node with
drbdadm adjust <resource>
You can then check to see if it worked (or to see other options if you're curious) with
drbdsetup /dev/drbd# show
Here are my preferred network options:
net {
after-sb-0pri discard-older-primary;
after-sb-1pri consensus;
always-asbp;
timeout 30;
connect-int 5;
ping-int 5;
}
Jdhutchin@ugcs.caltech.edu 22:08, 7 June 2008 (PDT)
