Luis, The disk only has the WAL (pg_xlog ) directory. Brett, Here are the mount options:
/dev/sdb1 on /storage/sdb1 type ext3 (rw,noatime,data=writeback,errors=remount-ro) BTW The original fs was ext4, now I am trying with ext3, with the exact same results. No noticeable changes using diferent journal modes. I also tried disabling the journal altogether, which dramatically reduced the disk usage, but nevertheless there was this latency spikes. On Mon, Jul 29, 2013 at 3:01 PM, Brett Stauner <br...@mightybs.net> wrote: > Okay, so it's not happening at the same time of day or anything. What are > your mount options for the WAL disk? > > > On Mon, Jul 29, 2013 at 12:58 PM, German Becker > <german.bec...@gmail.com>wrote: > >> >> Brett, >> >> Yes I'm not impying it is postgres related, perhaps is even a normal >> thing of ext3 /ext4 filesystem, but, this behavioiur is only notable when >> using postgres and in particular the wal files, as it is very hard disk >> intensive, soy maybe somenone has seen this befores. The server only task >> is the database. It has 4 disks one for the os, one for the wal and the >> other 2 for data. All disks show different access times. The WAL disk is >> the only one on which the with constant latency, and in certain ocasions it >> goes up. >> Plus the ocasions are absolutely random. >> >> On Mon, Jul 29, 2013 at 1:15 PM, Brett Stauner <br...@mightybs.net>wrote: >> >>> "...like if the disk/filesystem gets slower during one hour or so" >>> >>> What about a different scheduled task on the system, not necessarily >>> Postgres related? >>> >>> >>> On Mon, Jul 29, 2013 at 9:17 AM, German Becker >>> <german.bec...@gmail.com>wrote: >>> >>>> Alvaro, >>>> >>>> Thanks for your reply. I believe that the only possibility is autovacum >>>> activity I will check that. Anyway what puzzles me is that >>>> the throughput does not increase like i might expect if there where high >>>> VACUUM activity, only the WAIT TIME and thus the UTILIZATION. Is like if >>>> the disk/filesystem gets slower during one hour or so... >>>> >>>> >>>> On Fri, Jul 26, 2013 at 5:27 PM, Alvaro Herrera < >>>> alvhe...@2ndquadrant.com> wrote: >>>> >>>>> German Becker escribió: >>>>> > Hi list, >>>>> > >>>>> > I am running Postgres 9.1 on Ubuntu 12.04. I have a dedicated disk >>>>> for >>>>> > pg_xlog, using ext4 filesystem with journaling in writeback mode >>>>> > During high load times, the disk usage is arround 40%. The IO write >>>>> time is >>>>> > constant at about 3ms. On certain occasions roughly once in 15 >>>>> days, the >>>>> > IO write time goes up to about 10ms. This makes the disk usage go up >>>>> to >>>>> > almost 100%, probably saturation, and the INSERTS DELETES UPDATES run >>>>> > considerable slower than normal.This lasts for about 2 hours and >>>>> then the >>>>> > latency goes back to 3ms and everything is normal again. >>>>> > Has anyone seen this behavior? What could be causing the increase in >>>>> > latency? >>>>> >>>>> Can you correlate these episodes with autovacuum activity? Or perhaps >>>>> backups are being taken (maybe a new base backup is taken every 15 >>>>> days)? >>>>> >>>>> -- >>>>> Álvaro Herrera http://www.2ndQuadrant.com/ >>>>> PostgreSQL Development, 24x7 Support, Training & Services >>>>> >>>> >>>> >>> >> >
