[Beowulf] Poll - Directory implementation

[Prentice Bisbal]

nscd, nslcd, and sssd all provide the same functionality, so you should 
never have more than one of them running at once. RHEL5 used nscd. RHEL 
6 eliminate nscd and replaced it with sssd, but included nslcd. I'm no 
expert on nslcd (because I switched to sssd as soon as RHEL 6 came 
out),  but it appears to be the same or very similar to nscd, but only 
for LDAP.

Prentice

On 10/26/2018 10:13 PM, John Hearns via Beowulf wrote:
> Skylar, I believe that nscd does not work well with sssd and I 
> disabled it.
> See 
> 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.
>
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> On Sat, 27 Oct 2018 at 00:59, Skylar Thompson 
> <skylar.thompson at gmail.com <mailto:skylar.thompson at 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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