Re: Performance of MDB and BDB Please suggest?

[Quanah Gibson-Mount <quanah@zimbra.com>]

On Aug 24, 2012, at 7:19 AM, Chris Card <ctcard@hotmail.com> wrote:

> 
> 
> 
>>>>> I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb RAM.
>>>> 
>>>>> My test directory has ~ 3 million entries, and I loaded it into mdb using
>>>> slapadd which took over 2 days (by comparison, the same load into bdb takes
>>>> 2-3 hours).
>> 
>>>> This is not normal. With slapadd -q MDB is faster than BDB assuming you're
>>>> using a decent filesystem and sensible mount options. JFS, EXT2, do better
>>>> than other filesystems in my tests. Very recent EXT4 may be better than EXT3
>>>> as well.
>>> The filesystem is xfs, mounted as a drbd device (although at the moment the other
>>> half of the drbd pair is not configured, so it doesn't have to wait for synchronous
>>> writes across the network)
>> 
>> Sounds like you're not using slapadd -q. Either that, or your filesystem cache
> 
> Oh ****! You're quite right, I managed to lose the -q from the slapadd command when copy/pasting 
> from a script. I'll try running it again with -q.
> 
> Do you have an ETA for improvements to mdb write performance?
> 
> Chris                         
> 


In my testing, only a setting of "2" for tool threads when using MDB with slapadd made sense.  Any higher value degraded perf.  Also, current RE24 has one write perf change in it from Howard over 2.4.32 although I have not yet tested its impact any. It made some differences for Howard in his tests. 

--Quanah