Thread

1. Re: XFS File systems and PostgreSQL

   Robert E. Bruccoleri <bruc@stone.congenomics.com> — 2001-05-07T14:35:07Z

   I have run a simple PostgreSQL benchmark on my SGI system which uses
   XFS for its file system on all disks to compare the effect of fsync.
   The benchmark was the loading of a database from 157 MB of pg_dump data
   including the construction of 11 Btree indexes covering nearly all
   of the data. The second column was just for the data load,
   and the third column is for the index creation.
   The system is an SGI Indigo2 R10000 running Irix 6.5.7
   with 384 MB RAM writing to Seagate 18GB 7200RPM narrow SCSI disks.
   
   
   Fsync enabled	Elapsed load time	Elapsed indexing time
   Yes		      15:53			9:16
   No		      10:33			8:40
   
   The CPU is not fully utilized for loading, and thus the system is I/O
   bound and the use of fsync has an impact. By contrast, the indexing
   process is CPU bound, and fsync is less important.
   
   The performance penalty for using fsync is modest, and therefore,
   I do not believe that we should discourage people from using XFS
   because it is a journaling file system. The note advising against
   installing Postgres on XFS should be removed from the installation
   guide. Instead, we need to explore how to use XFS's features to improve
   PostgreSQL's performance. For example, the XFS filesystem journal can be
   placed on a drive different from the data drive. This would substantially
   improve write performance.
   
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2. Re: Re: XFS File systems and PostgreSQL

   Bruce Momjian <pgman@candle.pha.pa.us> — 2001-05-07T18:38:50Z

   > The performance penalty for using fsync is modest, and therefore,
   > I do not believe that we should discourage people from using XFS
   > because it is a journaling file system. The note advising against
   > installing Postgres on XFS should be removed from the installation
   > guide. Instead, we need to explore how to use XFS's features to improve
   
   I don't believe any mention has been made in the docs yet.  Seems we are
   still exploring this.
   
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