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[Linux-cluster] Re: Linux-cluster Digest, Vol 20, Issue 12


While you did not directly say you planned to do so in your post, I would not recommend running GFS as the underlying filesystem from which you share home directories via samba. SMB is stateful and not cluster aware, and when I implemented this last year I ran into repeated samba crashes and locking issues I could not resolve. Last I checked Redhat only supports sharing stateless NFS on top of GFS. I haven't inquired about this since linuxworld (August), so maybe the new cluster system handles samba better, but I would definitly try it under a good load in a test environmnet before rolling it out via production. If someone out there is succesfully sharing a GFS filesystem via samba (and doing something else on it at the same time, like webserving) I'd love to hear about it. Running a samba PDC should be fine though I would still recommend putting the netlogon share on another filesystem and mirroring it wherever you had BDCs.

eventually we simply went with an iSCSI-based san and heartbeat-based failover of samba. If you have an LDAP backend everything can be made redundant and you can eliminate SPOF without special kernels patches and the cluster requirements. of course, this does not help in load balancing (since the data isn't available to both nodes simultaneously) and heartbeat itself has a few quirks.

As for the support from redhat I think you'll find that the people on this mailing list as about as top notch as exist in the linux community and as long as you've done your homework you should be able to get very good help very quickly. but if you need someone to blame and someone else's ass to be on the line, well...

Date: Mon, 12 Dec 2005 14:27:29 -0500
From: D Canfield <canfield uindy edu>
Subject: [Linux-cluster] General GFS Advice?
To: linux-cluster redhat com
Message-ID: <439DCF21 4090802 uindy edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I'm just looking for a bit of general advice about GFS... We're
basically just looking to use it as a SAN-based replacement for NFS.
We've got a handful of servers that need constant read/write access to
our users' home directories (Samba PDC/BDC, web server, network terminal
servers, etc.), and we thought GFS might be a good replacement from a
performance and security standpoint, let alone removing the SPOF of our
main NFS/file server.  Another place we're thinking of using it is
underneath our mail servers, so that as we grow, SMTP deliveries (and
virus scanning) can happen on one machine while IMAP/POP connections can
be served through another.

Unfortunately, even at academic prices, Red Hat wants more per single
GFS node than I'm paying for twenty AS licenses, so I've been heading
down this road by building from the SRPMS.  I mostly have a 2-node test
cluster built under RHEL4, but a number of things have me a little bit
hesitant to move forward, so I'm wondering if some folks can offer some

For starters, is my intended use even appropriate for GFS?  It does seem
as though I'm looking to put an awful lot of overhead (with the cluster
management suite) onto these boxes just to eliminate a SPOF.

Another concern is that this list seems to have a lot more questions
posted than answers.  Are folks running into situations where
filesystems are hopelessly corrupted or that they've been unable to
recover from?  That's the impression I feel like I'm getting, but I
suppose a newbie to Linux in general could get the same impression from
reading the fedora lists out of context.    The last thing I want to do
is put something into production and then have unexplained fencing
occurences or filesystem errors.

Finally, Red Hat sales is laying it on pretty heavy that the reason the
GFS pricing is so high is because it's nearly impossible to install it
yourself.  That was particularly true before GFS landed in Fedora.  Now
the claim is just that it's very difficult to manage without a support
contract.  Is this just marketing, or does GFS really turn out to be a
nightmare to maintain?

Any insights people could provide would be appreciated.


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