Re: [SAGE] SMTP/POP/IMAP mail server redundancy

["Sam Johnston" <samj@aos.net.au>]

According to Alan Cox as of ~15 minutes ago:

<quote>
Oracle are actively working towards a public GPL'd release of their
cluster file system. That and other priorities persuaded me at least not
to worry about opengfs for the meantime.

OpenGFS seems fairly stable. It has serious performance problems working
with lots of small files however.
</quote>

I wonder if the same (small file) limitations exist with GFS itself, from
which OpenGFS was derived? If so it's not going to work all that well with
Maildir, and I'd rather use reiserfs.

Sharing disks is certainly dangerous with many (most?) applications.
Maildir itself is fine, but the files created by courier are probably not.
That said in combination with a heartbeat of some sort for failover it
makes for one less thing to worry about. You could always just share a
SCSI bus and mount/unmount via the heartbeat system but you'd want to be
sure nothing else (admins included) ever tried to mount the same
filesystem on multiple machines at the same time!

As most of my downtime is related to changes/updates and software faults
rather than the hardware itself I'm more likely to use a reliable box with
RAID and redundant power, and run a bunch of Debian instances on User Mode
Linux. Then I'll just (carefully) mount/unmount local filesystems as nodes
come up/down.

 - samj

-- 
Sam Johnston
Australian Online Solutions
1300 132 809

Stephen Schaefer said:
> ``They have products that do live replication.  In linevirtualization
> stuff, etc.''  Yes.  And they are deep, deep voodoo.  Programs/OS's not
> written to expect things to change out from under them tend to destroy
> data when data does change out from under them.  I'm not claiming it's
> impossible to do correctly, it's just very difficult.  Many of the
> issues are discussed by the makers of the distibuted file system GFS:
> http://www.sistina.com/products_GFS_publications.htmI've read about this
> stuff, but I've never had the need for enough 9's to try to use it.    -
> Stephen P. Schaefer
>
>
> ---------------------------------
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-- 
Sam Johnston
Australian Online Solutions
1300 132 809