Re: "Leaking" disk space on FreeBSD servers - Mailing list pgsql-general

From Kevin Grittner
Subject Re: "Leaking" disk space on FreeBSD servers
Date
Msg-id 1363803946.25227.YahooMailNeo@web162901.mail.bf1.yahoo.com
Whole thread Raw
In response to "Leaking" disk space on FreeBSD servers  (Dan Thomas <godders@gmail.com>)
Responses Re: "Leaking" disk space on FreeBSD servers
List pgsql-general
Dan Thomas <godders@gmail.com> wrote:

> We're seeing a problem with some of our FreeBSD/PostgreSQL
> servers "leaking" quite significant amounts of disk space:

> Stopping Postgres doesn't fix it, but rebooting does which points
> at the OS rather than PG to me. However, the leak is only
> apparent in the dedicated pgsql partition, and only on our
> database servers, so PostgreSQL seems to at least be involved.
> The partition itself is a relatively standard UFS partition:

I saw something once which *might* be related.  I don't recall the
OS of FS involved, but in an attempt to reduce the fragmentation of
files which started small and eventually grew large, a large
allocation of contiguous space was made on file creation, and that
space was not release as long as any page for the file remained in
the OS cache.  In the instance where I saw the problem, autovacuum
had been turned off and the instance was just coming up on the
point where wraparound prevention runs were about to be triggered.
pg_clog was where most of the wasted space was.

No guarantees that this is the issue, but it sounded similar....

--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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