ZFS-FreeBSD + postgresql performance

[Ronald Klop]

On Wed, 23 Oct 2013 18:25:45 +0200, Albert Shih <Albert.Shih at obspm.fr>  
wrote:

> Hi
>
> I would like to known if someone here have in production a FreeBSD server
> with postgresql and the FS for the data of postgresql is a ZFS pool.
>
> I'm going to buy some server with 96Go of Ram and a jbod of 12 disks (4To
> each)
>
> The purpose is to have everything on this zfs pool (except the system who
> still on classic raid). So to have
>
>     many jail (~20-30) running apache/mysql/etc.
>     one postgresql server with all data on the zfs.
>
> each jail use his own zfs partition. So I can use zfs send/received to  
> have
> a  mirror of everything in a other server.
>
> My question is about the performance, I known ZFS eat all memory he can
> have (or almost), so what append when we run database like postgresql and
> jail ? (it's also the reason of 96 Go ram).
>
> Sorry for cross-posting but it's about 3 differents things....
>
> Regards.
>
> JAS

Databases do a lot of sync writes, so it might be good to use a fast ZIL  
device (SSD).

Ronald.