From: Gnanakumar <gnanam@zoniac.com>
To: 'Tomas Vondra' <tv@fuzzy.cz>
To: 'Vitalii Tymchyshyn' <tivv00@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Write workload is causing severe slowdown in Production
Date: Thu, 22 Mar 2012 16:02:00 +0530
Message-ID: <008e01cd0817$06418680$12c49380$@com> (raw)
In-Reply-To: <dc1f59dfd626334d6f37d5a6ffb97bb9.squirrel@sq.gransy.com>
References: <006301cd07fd$358ebe40$a0ac3ac0$@com>
<4F6AF3FE.30407@gmail.com>
<dc1f59dfd626334d6f37d5a6ffb97bb9.squirrel@sq.gransy.com>
> There's a checkpoint_warning option. Set it to 3600 and you should get
> messages in the log. Correlate those to the issues (do they happen at the
> same time?).
After setting "checkpoint_warning" to 3600, can you explain on how do I correlate with the messages?
> If you can, install iotop and watch the processes that cause the I/O.
I tried installing "iotop", but it failed to run because it requires Linux >= 2.6.20. Our CentOS5.2 is 2.6.18-8.
> What we need is more details about your setup, especially
> - checkpoint_segments
> - checkpoint_timeout
> - shared_buffers
# - Memory -
shared_buffers=1536MB
# - Planner Cost Constants -
effective_cache_size = 4GB
# - Checkpoints -
checkpoint_segments=32
checkpoint_timeout=5min
checkpoint_warning=270s
# - Background writer -
bgwriter_delay = 200ms
bgwriter_lru_percent = 1.0
bgwriter_lru_maxpages = 5
bgwriter_all_percent = 0.333
bgwriter_all_maxpages = 5
> also it'd be nice to have samples from the vmstat/iostat and messages from
> the log.
Unfortunately, I don't have "exact" logs when the problem actually happened
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To: pgsql-performance@postgresql.org
Cc: gnanam@zoniac.com, tv@fuzzy.cz, tivv00@gmail.com
Subject: Re: Write workload is causing severe slowdown in Production
In-Reply-To: <008e01cd0817$06418680$12c49380$@com>
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