So, i'm not sure if this will be helpful, but it certainly can't hurt.
Last month i set up my first HA-NFS setup, backend for frontend PHP
servers. I had some previous experience with the
corosync/pacemaker/heartbeat/drbd suite - a rabbitmq setup a year ago,
and i set up the PHP frontend servers using the suite, before realizing
that an NFS backend would be more appropriate. Suffice to say that the
suite is dense, particularly the corosync crm configuration. It was a
challenging week of poking, prodding, relentless google searching and
discovery to get it all working. I referenced all documents others have
mentioned, possibly more! The document that really got me into the
'functioning' realm was the linbit pdf 'Highly available NFS storage
with DRBD and Pacemaker'. Even so, i made my own adjustments and
modifications to the described setup to make it happen.
On each server i had a spare LVM partition to use for drbd. Initially, i
thought that i *had to* use nested LVM's to make this work (
http://www.drbd.org/users-guide/s-nested-lvm.html ). That accounted for
a large part of the frustration. Eventually i learned (by trial and
mostly error) that i didn't have to use nested LVM's, i could just use
them as is.
In forcing a failover ('service corosync restart'), there's 15 to 20
seconds during which the frontend web falters, waiting on the other
corosync to see the failure, then remount on the other box. That's a
tolerable pause for me. I could probably lower that by tweaking the
various timeouts in the corosync config, but i haven't touched that yet
(i've been afraid to mess with it and break it!)
Below are each of the relevant configs and info, or snippets thereof
(eliding generally default stuff with '[...]'), in hopes that maybe they
will be of value to someone. this is all on centos 5.8. naturally, all
noted configs are identical between the two servers.
[root@nfs-a ~]# uname -a
Linux nfs-a 2.6.18-308.4.1.el5 #1 SMP Tue Apr 17 17:08:00 EDT 2012
x86_64 x86_64 x86_64 GNU/Linux
================================================================
[root@nfs-a ~]# rpm -qa|grep drbd;rpm -qa|grep corosync;rpm -qa|grep
heartbeat;rpm -qa|grep pacemaker
drbd83-8.3.13-2.el5.centos
kmod-drbd83-8.3.13-1.el5.centos
corosynclib-1.2.7-1.1.el5
corosync-1.2.7-1.1.el5
heartbeat-libs-3.0.3-2.3.el5
heartbeat-3.0.3-2.3.el5
pacemaker-libs-1.0.12-1.el5.centos
pacemaker-1.0.12-1.el5.centos
[root@nfs-a ~]#
================================================================
[root@nfs-a ~]# cat /etc/hosts
127.0.0.1 nfs-a localhost.localdomain localhost
10.255.20.58 nfs-a
10.255.20.59 nfs-b
10.255.20.204 nfs-shared
================================================================
[root@nfs-a ~]# df -h
Filesystem Size Used Avail Use% Mounted on
[...]
/dev/drbd1 20G 537M 18G 3% /srv/nfs/html
================================================================
[root@nfs-b ~]# df -h
Filesystem Size Used Avail Use% Mounted on
[...]
================================================================
[root@nfs-a ~]# cat /proc/drbd
version: 8.3.13 (api:88/proto:86-96)
GIT-hash: 83ca112086600faacab2f157bc5a9324f7bd7f77 build by
[email protected], 2012-05-07 11:56:36
1: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
ns:3755180 nr:3535432 dw:7290612 dr:156289 al:179 bm:10 lo:0 pe:0
ua:0 ap:0 ep:1 wo:f oos:0
================================================================
[root@nfs-a ~]# cat /etc/drbd.d/global_common.conf
[...]
common {
startup {
wfc-timeout 0; degr-wfc-timeout 120;
}
disk {
on-io-error detach;
}
syncer {
rate 200M; al-extents 257;
}
================================================================
[root@nfs-a ~]# cat /etc/drbd.d/resources.res
resource nfs-volume {
device /dev/drbd1;
disk /dev/VolGroup00/LogVol02; # the actual disk partition
meta-disk internal;
# use canonical hostname for 'on <something>'
on nfs-a {
address 10.255.20.58:7789;
}
# use canonical hostname for 'on <something>'
on nfs-b {
address 10.255.20.59:7789;
}
}
================================================================
[root@nfs-a ~]# lvdisplay
[...]
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol02
VG Name VolGroup00
LV UUID c46CsV-bOmj-6idR-I48H-7O3t-48e3-wKrfVh
LV Write Access read/write
LV Status available
# open 2
LV Size 19.53 GB
Current LE 625
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
================================================================
[root@nfs-a ~]# cat /etc/ha.d/ha.cf
[...]
# Communications
udpport 698 # Change last digit so that it
doesn't
# conflict with another instance
of HA
bcast eth0
[...]
================================================================
In /etc/lvm/lvm.conf, *no* filtering, contrary to the guide
================================================================
[root@nfs-a ~]# cat /etc/corosync/corosync.conf
totem {
[...]
interface {
ringnumber: 0
# The following three values need to be set based on
your environment
bindnetaddr: 10.255.20.0 # your local subnet
mcastaddr: 226.94.1.58 # set last octet to
last octet of one of the
# server's IP's. This
prevents conflict with
# other corosyncs that
may be running on same network
mcastport: 5405
[...]
================================================================
Finally the working crm configuration. Note that i used different
mnemonics for primitives, etc, as the guide's use of all lowercase just
made it all swim in front of my eyes. :)
node nfs-a
node nfs-b
primitive DAEMON lsb:nfs \
op monitor interval="30" \
meta target-role="Started"
primitive DRBD ocf:linbit:drbd \
params drbd_resource="nfs-volume" \
op start interval="0" timeout="240" \
op stop interval="0" timeout="100" \
op monitor interval="15" role="Master" \
op monitor interval="30" role="Slave"
primitive EXPORT ocf:heartbeat:exportfs \
params fsid="1" directory="/srv/nfs/html"
options="rw,mountpoint,no_root_squash" \
clientspec="10.255.20.0/255.255.255.0"
wait_for_leasetime_on_stop="true" \
op monitor interval="0" timeout="40" \
op start interval="0" timeout="40" \
meta target-role="Started"
primitive FILESYSTEM ocf:heartbeat:Filesystem \
params device="/dev/drbd1" directory="/srv/nfs/html"
fstype="ext4" \
options="nobarrier,noatime" \
op monitor interval="10" timeout="40" \
op start interval="0" timeout="240" \
op stop interval="0" timeout="100" \
meta target-role="Started"
primitive VIRTUALIP ocf:heartbeat:IPaddr2 \
params ip="10.255.20.204" broadcast="10.255.20.255"
nic="eth0:1" cidr_netmask="24" \
op monitor interval="30" \
meta target-role="Started"
ms msDRBD DRBD \
meta master-max="1" master-node-max="1" clone-max="2"
clone-node-max="1" notify="true" \
is-managed="true" target-role="Master"
clone clDAEMON DAEMON
clone clEXPORT EXPORT
colocation NFSALL-on-msDRBD inf: clDAEMON clEXPORT FILESYSTEM VIRTUALIP
msDRBD:Master
order msDRBD-before-FILESYSTEM inf: msDRBD:promote FILESYSTEM:start
order FILESYSTEM-before-clDAEMON inf: FILESYSTEM clDAEMON
order clDAEMON-before-clEXPORT inf: clDAEMON clEXPORT
order clEXPORT-before-VIRTUALIP inf: clEXPORT VIRTUALIP
property $id="cib-bootstrap-options" \
dc-version="1.0.12-unknown" \
cluster-infrastructure="openais" \
expected-quorum-votes="2" \
stonith-enabled="false" \
no-quorum-policy="ignore" \
last-lrm-refresh="1338327933"
rsc_defaults $id="rsc-options" \
resource-stickiness="200"
================================================================
[root@nfs-a etc]# crm status
============
Last updated: Wed Jun 6 17:01:29 2012
Stack: openais
Current DC: nfs-a - partition with quorum
Version: 1.0.12-unknown
2 Nodes configured, 2 expected votes
5 Resources configured.
============
Online: [ nfs-a nfs-b ]
FILESYSTEM (ocf::heartbeat:Filesystem): Started nfs-a
VIRTUALIP (ocf::heartbeat:IPaddr2): Started nfs-a
Master/Slave Set: msDRBD
Masters: [ nfs-a ]
Slaves: [ nfs-b ]
Clone Set: clDAEMON
Started: [ nfs-a ]
Stopped: [ DAEMON:1 ]
Clone Set: clEXPORT
Started: [ nfs-a ]
Stopped: [ EXPORT:1 ]
--
Paul Theodoropoulos
www.anastrophe.com
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