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help / color / mirror / Atom feedFrom: Bruce Momjian <[email protected]>
To: PostgreSQL-documentation <[email protected]>
Subject: effective_io_concurrency and SSDs
Date: Thu, 18 Feb 2016 19:19:57 -0500
Message-ID: <[email protected]> (raw)
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I have created the attached doc patch to update effective_io_concurrency
to more accurately cover SSDs.
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Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
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Attachments:
[text/x-diff] ssd.diff (1.9K, 2-ssd.diff)
download | inline diff:
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index a09ceb2..feb3777
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** include_dir 'conf.d'
*** 1876,1895 ****
</para>
<para>
! A good starting point for this setting is the number of separate
drives comprising a RAID 0 stripe or RAID 1 mirror being used for the
database. (For RAID 5 the parity drive should not be counted.)
However, if the database is often busy with multiple queries issued in
concurrent sessions, lower values may be sufficient to keep the disk
array busy. A value higher than needed to keep the disks busy will
only result in extra CPU overhead.
! </para>
!
! <para>
! For more exotic systems, such as memory-based storage or a RAID array
! that is limited by bus bandwidth, the correct value might be the
! number of I/O paths available. Some experimentation may be needed
! to find the best value.
</para>
<para>
--- 1876,1891 ----
</para>
<para>
! For magnetic drives, a good starting point for this setting is the
! number of separate
drives comprising a RAID 0 stripe or RAID 1 mirror being used for the
database. (For RAID 5 the parity drive should not be counted.)
However, if the database is often busy with multiple queries issued in
concurrent sessions, lower values may be sufficient to keep the disk
array busy. A value higher than needed to keep the disks busy will
only result in extra CPU overhead.
! SSDs and other memory-based storage can often process many
! concurrent requests, so the best value might be in the hundreds.
</para>
<para>
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