On 12/12/14 11:36, Eric Pierce wrote:
________________________________________
From: pgsql-performance-ow...@postgresql.org <pgsql-performance-ow...@postgresql.org>
on behalf of Evgeniy Shishkin <itparan...@gmail.com>
Sent: Thursday, December 11, 2014 7:11 AM
To: Andrea Suisani
Cc: mfatticci...@mbigroup.it; pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Tuning the configuration
On 11 Dec 2014, at 15:02, Andrea Suisani <sick...@opinioni.net> wrote:
On 12/10/2014 11:44 AM, Maila Fatticcioni wrote:
2- I would like to use the two SDD to store the wal file. Do you think
it is useful or how should I use them?
I definitely would give it a try.
I don't understand the logic behind using drives,
which are best for random io, for sequent io workloads.
Better use 10k sas with BBU raid for wal, money wise.
Very much agree with this. Because SSD is fast doesn't make it suited for
certain things, and a streaming sequential 100% write workload is one of them.
I've worked with everything from local disk to high-end SAN and even at the
high end we've always put any DB logs on spinning disk. RAID1 is generally
sufficient. SSD is king for read heavy random I/O workload.
Mind you wal is a little different - the limiting factor is (usually)
not raw sequential speed but fsync latency. These days a modern SSD has
fsync response pretty much equal to that of a card with BBU + spinners -
and has "more" high speed storage available (cards usually have only a
1G or so of RAM on them).
regards
Mark
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
