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Re: db stick in RAM ?

Frank Bonnet wrote:

   Hello

Yes maybe safier to use slapcat ...

I haven't any SSDs for now so I tested ramdisk
did you perform tests with SSD ?
A good SSD can work, but it will cost quite a bit and RAM is still an order of magnitude faster. Also, most of the SSDs available now are still poor for random writes, which is the main performance bottleneck. (All of my PCs are on SSDs now; they're great for fast boot times but without a big RAM cache they're still dog slow.) 

thanks

On 10/19/2010 11:00 AM, Benjamin Griese wrote:

Hi Frank,

by rsync to hdd, do you mean copying the db files or slapcat the
output to a file?
The first one seems to be a db killer if the db is in use while copying it. :)
I think the only safe way is by doing a slapcat after every write to
the db (accesslog?).

Anyway, sounds like a nice idea to me to get a big performance boost.
Have you considered SSDs instead of ramdisks?
Imo its the more safe and nearly as fast as ramdisk alternative. :)

Bye, Benjamin.

On Tue, Oct 19, 2010 at 10:40, Frank Bonnet<f.bonnet@esiee.fr>   wrote:

Hello

I'm thinking to put db files in RAM instead of hard disk
for performance reasons.

FreeBSD ( and Linux thought ) provide some utility to build
RAMDISK ( md )

I did some tests in rebuilding db files with the slapcat/slapadd
commands

with RAMDISK

ldap3# time slapadd -l test.ldif
/usr/local/etc/openldap/slapd.conf: line 110: rootdn is always granted
unlimited privileges.
#################### 100.00% eta   none elapsed             20s spd 633.9
k/s

WITH HARDDISK

ldap3# time slapadd -l test.ldif
/usr/local/etc/openldap/slapd.conf: line 110: rootdn is always granted
unlimited privileges.
#################### 100.00% eta   none elapsed          04m22s spd  48.4
k/s

Does anyone runs production servers with ramdisk ?

I know it is risky but running rsyncd between ramdisk and a hardisk depot
would be safe huh ?

Thanks for any advices










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