Hi DAve;
-----Original Message-----
From: DAve [mailto:[EMAIL PROTECTED]
Sent: Friday, October 05, 2007 11:39 AM
To: vpopmail
Subject: [vchkpw] My single point of failure... failed
I got bit hard this morning and I am looking for a solution. I have
been
slowly getting our email system up to snuff moving from a pair of
servers to two gateway AV scanners, three vpopmail toasters, and two
outbound qmail servers. The toasters mount the Maildirs via NFS, the
AV
scanners talk to the toasters via milter-ahead, and the NFS mailstore
hosts MySQL for vpopmail.
I've just gotten load balancers installed and moved the outbound
traffic
there first, getting a good load test on vpopmaild for smtp-auth. I
had
promised to provide the scripts and now I am actually seeing how well
they work.
Problems arose when my NFS server went stupid this morning and all
mail
stopped. AV scanners couldn't verify mailboxes because the toasters
couldn't see MySQL, the outbound servers couldn't do smtp-auth for the
same reason. It wouldn't have mattered anyway because my Maildirs were
offline. NFS is my single point of failure, even though it is RAID5,
dual NIC, dual power supply (SUN Enterprise 250), it went offline.
I need to fix that, I can cluster MySQL but I am looking for ways to
have either a clustered NFS with rw permissions and appropriate
locking/syncing, or NFS failover from the toasters.
I am looking at GFS and active/active NFS and HaNFS. Has anyone gone
down this path yet?
I have. There's a couple ways of doing this. I've never played with
GFS so I can't comment on that. The easiest solution I've found is
doing an Active/Standby configuration between 2 nodes using DRBD to
replicate the data in real time. There's quite a few solutions out
there to handle resource seizure on node failure. If you want
absolutely simple, go heartbeat v1. If you want to break your mailstore
into 2 pieces (I have no idea how large of a mailstore you're working
with. Mine is breaking 70G pretty soon) then you can do an
Active/Active configuration using the High Availability manager from
LinuxHA.net. I like that product mainly because it's written
specifically for 2 node active/active clusters. And if you really want
to muddy the waters, you can go with heartbeat v2 (I still have a bad
taste in my mouth from it though)
It's always best to keep major components on their own sets of boxen.
My MySQL servers are a 2 node load balanced multi-master replicated
pair. My Mailstore is a 2 node Active/Passive pair as described above
(I cheat a bit and do some iSCSI exports on the "passive" box to the
Windows people who demanded I share my storage with them. It's also
handled by the HA software, so if the box exporting the iSCSI targets
goes down, it shuffles across to the NFS box, and vice-versa)
My inbound/outbound SMTP is across 4 dedicated load-balanced boxen.
IMAP4(s)/POP3(s) is on its own pair and same with Web.
If any of this seems useful to you let me know. No one should have to
go through the nightmare of a key server going down. I hate getting
yelled at. :)
