Mailinglist Archive: opensuse-ha (30 mails)

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Re: [opensuse-ha] ext4 failure on cluster
On 2014-08-15T13:39:45, steve <steve@xxxxxxxxxxxx> wrote:

Other setups use it:
http://sigterm.sh/2014/02/highly-available-nfs-cluster-on-debian-wheezy/

But that's not what they are doing. They are only mounting it once; with
drbd (in normal configuration) it's only possible to write to the device
once anyway, so no-concurrent mount would be possible anyway.
Ok, I see: they are using fail over only? Presumably they will have only
one node up at a time. Is that what you term local file system? Or is
that something else? It's as clear as mud over here, sorry!

Right. A traditional "local" file system can only be mounted on one node
at once without crashing.

In our case, we have drbd primary:primary with the data mounted on both
nodes at the same time. Is it that configuration which cashes ext4?

Yes. This does not work and causes data corruption and crashes.

With ocfs2, it's fine. It still works though, even if we disable one
of the nodes. We have only old hardware so it would be pointless
having ext4 nodes with only one active at a time: we may as well go
back to our single file server.

I'm not sure this holds. There's a penalty needed for syncing and
locking. Have you benchmarked if a single node is really slower than
two? Especially a write-heavy workload probably won't, and it'll go very
much downhill if you have metadata-intensive jobs (e.g.,
creating/deleting/stating lots of files/directories).

The main reason for HA is, well, availability, not performance, thus
going back to a single server is likely worse than this anyway.


Regards,
Lars

--
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imend├Ârffer, HRB
21284 (AG N├╝rnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde

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