On 26 Sep 2012, at 22:36, Quanah Gibson-Mount wrote:
--On Wednesday, September 26, 2012 11:59 AM +0100 Mark Cairney
> My olcDB values are listed below (minus the olcDbConfig entries). I'm not
> sure if you need the indexes but I've left them in anyway:
> olcDbCacheFree: 1
> olcDbCacheSize: 400000
> olcDbIDLcacheSize: 1200000
> set_cachesize 4 0 1
This may be a little small. I prefer to fully cache my DB.
Which one in particular? I thought the set_cachesize had an upper limit of 4GB but your
guidance on the Zimbra website suggests this is an old limit and I now can't find the
page on the OpenLDAP site which discusses it. Alternatively would increasing the number of
caches from 2 to 2 or 3 be a suitable workaround?
Given that I've got a relatively healthy amount of RAM available would the following
sound sensible to you
set_cachesize 4 0 2
I also want to give a bit of headroom for new user accounts (approx rate of increase
80,000/y) and creating a group object for each user.
> I'm not using an SHM key (should I be?).
So with 300,000 users, your caches look fine. I would definitely recommend using an SHM
key if you are going to stick with using BDB. I personally prefer using MDB with current
RE24 these days. It is magnitudes faster than BDB in all aspects if you enable write map.
I've looked at your guidance on using SHM keys but I'm slightly reluctant to start
playing around with kernel settings on production servers :-)
The existing default settings on RHEL 5 seem massive in comparison though:
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
Whereas based on the ZImbra performance tuning page I calculated (based on 8GB BDB cache
size + 0.5GB for other stuff)
shmall would be: 2228224
and shmmax: 8589934592
Both of which appear to be an order of magnitude smaller than the defaults!
Then there appears to be some Zimbra-specific commands but I'm guessing the equivalent
is just setting the olcDBShmKey in slapd.d on vanilla OpenLDAP?
My plan in the longer term is to move to MDB but when I tried it out on one of our test
VMs (40GB HD) it pretty much devoured all available disk space. Is there a rule of thumb
for deriving probable MDB disk space requirements based on existing BDB size?
Thanks for the help and apologies for all the additional questions!
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