[Samba] URGENT CTDB: Which event scripts MUST be enable?

[Robert Buck]

Very helpful. Thank you, Martin!

On Mon, Jan 11, 2021 at 9:21 PM Martin Schwenke <martin at meltin.net> wrote:

> Hi Bob,
>
> On Mon, 11 Jan 2021 18:18:05 -0500, Robert Buck via samba
> <samba at lists.samba.org> wrote:
>
> > We're using CTDB with winbind and samba.
> >
> > What event scripts of these MUST be enabled?
> >
> > # ctdb event script list legacy
> >   00.ctdb
> >   01.reclock
> >   05.system
> >   06.nfs
> >   10.interface
> >   11.natgw
> >   11.routing
> >   13.per_ip_routing
> >   20.multipathd
> >   31.clamd
> >   40.vsftpd
> >   41.httpd
> >
> > ** 49.winbind* 50.samba*
> >   60.nfs
> >   70.iscsi
> >   91.lvs
> >
> > Are we supposed to enable reclock, system, or ctdb?
>
> Since you're using winbindd and smbd you almost certainly want
> 49.winbind and 50.samba to be enabled.  However, it is possible to
> start/stop/monitor these services using some other custom mechanism, so
> disabling them is not out of the question.
>
> * 00.ctdb is considered mandatory
>
>   It does several things:
>
>   - Checks for corrupt TDB files... so corrupt, volatile TDBs can be
>     backed up for later analysis
>
>   - Creates $CTDB_SCRIPT_VARDIR, which is used by other scripts to
>     store state
>
>   - Processes /etc/ctdb/ctdb.tunables (or similar)
>
>   - Attaches ctdb.tdb, which is only current used by statd-callout,
>     when using NFS
>
>   The documentation clearly needs to be improved.  :-(
>
>   Both ctdb/wscript (used by "make install") and
>   ctdb/packaging/RPM/ctdb.spec.in (may be used to build standalone RPM
>   package(s)) attempt to ensure that this script is enabled.
>
> * 01.reclock is only really used to create the directory containing the
>   recovery lock
>
>   If you're using a helper (via "! ..." syntax) then you don't need
>   this.
>
>   The comment at the top of this script has bit-rotted.  :-(
>
>   01.reclock is enabled by default at first-time install since we don't
>   know how the recovery lock will be configured.
>
> * 05.system is used to monitor system resources
>
>   If you have better resource monitoring in place then you can happily
>   disable this script.
>
>   05.system is enabled by default at first-time install because
>   we have seen many cases where performance issues and other issues
>   have been reported, there is a resource problem on a node and the
>   user is blissfully unaware... and blames CTDB for performing badly.
>   The entire purpose of this script is for us to be able to look at
>   someone's logs and say "performance was bad because you ran out of
>   memory" or similar.  ;-)
>
> * 10.interface is used to manage public IP addresses
>
>   This monitors interfaces and, when directed by the daemon, "moves"
>   public IP addresses
>
>   I think that in a previous email you said that you are current unable
>   to use CTDB's public IP addresses, so you probably don't need this.
>
>   10.interface is enabled by default at first-time install because we
>   assume most people will use public IP addresses.
>
> peace & happiness,
> martin
>
>

-- 

BOB BUCK
SENIOR PLATFORM SOFTWARE ENGINEER

SKIDMORE, OWINGS & MERRILL
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T  (212) 298-9624
ROBERT.BUCK at SOM.COM