NFS
Contents |
pmtpa
/home
The server
A DRBD cluster of nfs1 and nfs2 serve NFS /home. (At most) one of the two is primary at any point in time, and can read and write from the block device /dev/drbd1. The (other) secondary host can not write nor read from the block device... so /home cannot be mounted from it while the host is secondary.
DRBD has excellent documentation, and repeating that here would be pointless. The most common administrative tasks are described here.
/etc/drbd.conf (must always be equal on both hosts):
# drbd.conf for replication between nfs1 and nfs2
# Written on 2009/11/23 by Mark Bergsma <mark@wikimedia.org>
global {
usage-count no;
}
common {
protocol C;
}
resource nfshome {
syncer {
rate 110M;
}
on nfs1 {
device /dev/drbd1;
disk /dev/mapper/mirror-nfshome;
address 10.3.0.1:7789;
meta-disk internal;
}
on nfs2 {
device /dev/drbd1;
disk /dev/mapper/mirror-nfshome;
address 10.3.0.2:7789;
meta-disk internal;
}
}
The migration of NFS home off db20 onto nfs1/nfs2 was described extensively in the Db20 to NFS1-2 migration plan.
If the primary host goes down, the secondary can be promoted to primary. Use the following steps:
On the (failing?) primary (if accessible):
- Stop nfs-kernel-server
- Umount /home (so /dev/drbd1 is unused)
- drbdadm secondary nfshome
On the secondary, to become the new primary host:
- drbdadm primary nfshome
- Mount /home (uncomment in /etc/fstab)
- Start nfs-kernel-server
- Then, migrate the service ip 10.0.5.8 to the appropriate host.
Clients
/etc/fstab entry:
10.0.5.8:/home /home nfs bg,soft,udp,rsize=8192,wsize=8192,timeo=14,intr,nfsvers=3 0 0
Upload mounts:
amane:/export/upload /mnt/upload3 nfs bg,soft,udp,rsize=8192,wsize=8192,timeo=14,intr,nfsvers=3 0 0 storage1.wikimedia.org:/export/upload /mnt/upload4 nfs bg,soft,tcp,rsize=8192,wsize=8192,timeo=14 0 0
texvc output:
amane:/export/math /mnt/math nfs bg,soft,udp,rsize=8192,wsize=8192,timeo=14,intr,nfsvers=3 0 0
yaseo
No NFS anymore.
knams
Probably none. None on the squids anyway.
