On 10/27/2018 03:08 AM, John Hearns via Beowulf wrote:
To be clear I am talking about the Name Service Cacheing Daemon
I have always found this to be more trouble than it is worth - it
holds on to out of date information,
and needs to be restarted when you are debugging things like batch
systems etc.
My favorite feature of nscd was the paranoid option:
*paranoia* /<yes|no>/
Enabling paranoia mode causes nscd to restart itself periodically.
The default is no.
In practice, you need this. Otherwise, nscd will eventually hang,
requiring you to login as root and manually restart nscd. When you see
software with a feature like this, you know it's unreliable.
nslcd is something completely different (*) and whoever chose
similar names should be forced to watch endless re-runs of the Parrot
Sketch.
https://wiki.samba.org/index.php/Nslcd
(*) obligatory Python reference
Well, that corrects my statement in my last e-mail. nslcd always looked
just like nscd to me.
Prentice
On Sat, 27 Oct 2018 at 04:12, Skylar Thompson
<skylar.thomp...@gmail.com <mailto:skylar.thomp...@gmail.com>> wrote:
Good to know - we're still nslcd users so have yet to run into
that, though
are about to make the leap to CentOS 7 where I think we will have
to use
it.
On Sat, Oct 27, 2018 at 03:13:47AM +0100, John Hearns via Beowulf
wrote:
> Skylar, I believe that nscd does not work well with sssd and
I disabled
> it.
> See
[1]https://access.redhat.com/documentation/en-us/red_hat_enterprise
> _linux/6/html/deployment_guide/usingnscd-sssd
> I believe that nscd is the work of Auld Nick himself and
causes more
> problems than it is worth on HPC nodes.
> If you want to speed up cacheing with sssd itself you can put
its local
> caches on a RAMdisk. This has the cost of no persistence of
course and
> uses up RAM which you may prefer to put to better use.
>
> On Sat, 27 Oct 2018 at 00:59, Skylar Thompson
> <[2]skylar.thomp...@gmail.com
<mailto:skylar.thomp...@gmail.com>> wrote:
>
> On Fri, Oct 26, 2018 at 08:44:28PM +0000, Ryan Novosielski
wrote:
> > Our LDAP is very small, compared to the sorts of things some
> people run.
> >
> > We added indexes today on uid, uidNumber, and gidNumber
and the
> problem went away. Didn’t try it earlier as it had virtually no
> impact on our testing system for whatever reason, but on a
different
> testing system and on production, it dropped “ls -al
/home/“ from
> ~90s to ~5s. I’m not sure if all three were necessary, but
I’ll look
> back at that later.
> >
> > We’ve run SSSD from day one, so that eliminates the nscld
> question. We also moved CentOS 5.x to SSSD, FYI (I believe
there was
> someone else with some old systems around). Was pretty
painless, and
> SSSD eliminates a lot of problems that exist with the older
stuff
> (including some really boneheaded very large LDAP queries
that were
> happening routinely with the older nss-ldap software if I’m
> remembering its name correctly).
> Have you experimented with client-side caching services
like nscd?
> nscd has
> its quirks (in particular, it does very poorly with caching
spurious
> negative
> results from transient network failures), but it also is a big
> performance
> improvement since you don't even have to hit the network or the
> directory
> services.
> --
> Skylar
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> References
>
> 1.
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/usingnscd-sssd
> 2. mailto:skylar.thomp...@gmail.com
<mailto:skylar.thomp...@gmail.com>
> 3. mailto:Beowulf@beowulf.org <mailto:Beowulf@beowulf.org>
> 4. http://www.beowulf.org/mailman/listinfo/beowulf
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--
Skylar
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