Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
I am in the beginning stage of planing a high availability environment. I have
some general questions about deployment. Any suggestions or comments
are welcomed.
I have two servers connected to a shared storage device (server1 and server2).
We also have a 'slave' machine on the network which I would like to have all
data duplicated to in case of an 'emergency'.
My main concern is the the 'slave' remains a secondary at all times until I
change it manually as the primary in the event of an 'emergency'. Do I need
to change anything in my drdb.conf to make this happen. What about reboots?
Or should I make a startup file which executes "drbdadm secondary all"
on the 'slave' machine?
Also I question on how heartbeat/drbd handles the exchange of drbd primary
on the heartbeat cluster. The scenario is 'server1' had /dev/drdb0 mounted and
is the primary. 'Server1' has problems and heartbeat transfers resources to
'server2' via the haresources. (we have stonith network powerswitch to take care
of dual mounts).
haresources:
==========
server1 datadisk::drbd0 Filesystem::/dev/drbd0::/home Filesystem::/dev/sda1::/usr/local/apache 192.168.0.1 apache
server2 Filesystem::/dev/sda3::/usr/local/mysql 192.168.0.2 mysql
Does 'server2' automatically become primary? Will the 'slave' still remain secondary the
whole time? Is the same true with the heartbeat event of auto_failback? Or should I
put a "drbdadm primary all" in my apache init.d file?
The mysql database has built-in replication happening with the slave machine.
Also the data is saved once an hour with mysql_dump. It it possible to replicate
the data in /usr/local/mysql database with drbd? Could this cause corruption/unreliability
in the database files located on the slave node?
Here are my config files. Any feedback is greatly appreciated.
drbd.conf
==========================================================
resource drbd0 {
protocol B;
startup {
degr-wfc-timeout 120; # 2 minutes.
}
disk {
on-io-error detach;
}
net {
on-disconnect reconnect;
}
syncer {
rate 100M;
}
on cluster {
device /dev/drbd0;
disk /dev/sda4;
address 192.168.0.1:7788;
meta-disk internal;
}
on slave {
device /dev/drbd0;
disk /dev/hdc1;
address 192.168.1.200:7788;
meta-disk internal;
}
}
ha.cf
====================================
logfacility daemon
node server1 server2
keepalive 1
deadtime 10
bcast eth0
ping 192.168.1.254
auto_failback yes
respawn hacluster /usr/lib/heartbeat/ipfail
stonith apcmaster /etc/ha.d/apcmaster.conf
stonith_host * apcmaster xxx.xxx.xxx.xxx username password
Tim Hibbard
Software Engineer For
Vice President Of Research
Ohio University
Athens, Ohio 45701
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