[Beowulf] Poll - Directory implementation

John Hearns hearnsj at googlemail.com
Fri Oct 26 19:13:47 PDT 2018

Skylar, I believe that nscd does not work well with sssd and I disabled it.

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 <skylar.thompson at gmail.com>

> 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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