samba - Mar 2016 - Where are People Storing CTDB's Accounting Files?

Hi All,


We're using CTDB to cluster protocols over a large SAN and have had some
pain related to a bit of a design flaw:  we store CTDB and protocol-specific
accounting files (recovery locks, state files, etc) on the same filesystem that
we're offering through CTDB itself.  This makes our front-end services
pretty intolerant of flapping in the back-end filesystem, which is obviously not
desirable.


We're planning a redesign for this and were wondering what other people in
similar environments are doing with the their CTDB shared files.  Specifically,
I'm referring to the locations supplied for <shared_dir> in these
variables:


/etc/sysconfig/ctdb: CTDB_RECOVERY_LOCK=<shared_dir>


/etc/sysconfig/nfs: STATD_HOSTNAME=$NFS_HOSTNAME -P <shared_dir> -H
/etc/ctdb/statd-callout


/etc/sysconfig/nfs: NFS_TICKLE_SHARED_DIRECTORY=<shared_dir>


/etc/sysconfig/nfs: STATD_SHARED_DIRECTORY=<shared_dir>


Thanks!


Stewart

Hi Stewart,

On Sat, Mar 19, 2016 at 6:21 AM, Howard, Stewart Jameson <sjhoward at
iu.edu>
wrote:
> Hi All,
>
>
> We're using CTDB to cluster protocols over a large SAN and have had
some
> pain related to a bit of a design flaw:  we store CTDB and
> protocol-specific accounting files (recovery locks, state files, etc) on
> the same filesystem that we're offering through CTDB itself.  This
makes
> our front-end services pretty intolerant of flapping in the back-end
> filesystem, which is obviously not desirable.
>
If the backend storage and filesystem is not stable or reliable, then I
would advise against storing any state in the shared filesystem.

>
>
> We're planning a redesign for this and were wondering what other people
in
> similar environments are doing with the their CTDB shared files.
> Specifically, I'm referring to the locations supplied for
<shared_dir> in
> these variables:
>
>
> /etc/sysconfig/ctdb: CTDB_RECOVERY_LOCK=<shared_dir>
>
>
> /etc/sysconfig/nfs: STATD_HOSTNAME=$NFS_HOSTNAME -P <shared_dir> -H
> /etc/ctdb/statd-callout
>
>
> /etc/sysconfig/nfs: NFS_TICKLE_SHARED_DIRECTORY=<shared_dir>
>
>
> /etc/sysconfig/nfs: STATD_SHARED_DIRECTORY=<shared_dir>
>
>
Looks like you are using very old version of CTDB.  Some of the config
variables you have mentioned do not exist anymore.  The way CTDB manages
kernel nfsd has changed substantially and does not require storing any
state in the shared filesystem.

The latest CTDB versions use shared file system only for storing recovery
lock.  CTDB is pretty tolerant when checking for recovery lock on the
shared file system.  However, if you still notice problems, then CTDB can
work even without recovery lock.

Amitay.