On Mon, Jul 26, 2010 at 12:40 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> Greg Spiegelberg wrote:
>>
>> Speaking of the layers in-between, has this test been done with the ext3
>> journal on a different device? Maybe the purpose is wrong for the SSD. Use
>> the SSD for the ext3 journal and the spindled drives for filesystem?
>
> The main disk bottleneck on PostgreSQL databases are the random seeks for
> reading and writing to the main data blocks. The journal information is
> practically noise in comparison--it barely matters because it's so much less
> difficult to keep up with. This is why I don't really find ext2 interesting
> either.
Note that SSDs aren't usually real fast at large sequential writes
though, so it might be worth putting pg_xlog on a spinning pair in a
mirror and seeing how much, if any, the SSD drive speeds up when not
having to do pg_xlog.
