Re: db stick in RAM ?

[Benjamin Griese <der.darude@gmail.com>]

Doesn't that depend on the use case.
My knowledge about using OpenLDAP is mostly in 99% read and just 1%
write operations, while a SSD is very good in 99% of the operations
and only 1% writes, which is also cached in RAM.

It's bad if a SSDs takes its time for 1% writing as long as 99%
reading, thats smells like a little bit of benchmarking. :)

Bye.

On Tue, Oct 19, 2010 at 11:32, Howard Chu <hyc@symas.com> wrote:
> 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
>>>>
>>>>
>>>
>>>
>>
>
>
> --
>  -- Howard Chu
>  CTO, Symas Corp.           http://www.symas.com
>  Director, Highland Sun     http://highlandsun.com/hyc/
>  Chief Architect, OpenLDAP  http://www.openldap.org/project/
>



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