Renato Oliveira <renato.oliveira@xxxxxxxxxxx> wrote: > I have been testing PITR and I have noticed a 20% increase on the > load of the Disk subsystem. > > Is that a normal thing to expect? It depends on your workload and archive script, but that doesn't seem too shocking. For one thing, turning on archiving causes more to be written to the WAL files, so you should expect some increase just by enabling archiving, even if your archive script just consists of 'exit 0'. Reading the WAL file in the archive script will often be reading from OS cache, but not necessarily. If you're copying the WAL files to a local file system (which often makes sense), that obviously increases I/O. If there's enough delay between the archive script writing the file to a local drive and something (e.g., rsync) picking it up, it might need to read from the disk, and rsync is likely to do some logging. I would be surprised if you couldn't measure any increase, and 20% is certainly within a reasonable range, depending on all the above. If you need to try to minimize the impact, besides considering all of the above, you might want to look at the full_page_writes configuration option. http://www.postgresql.org/docs/8.4/interactive/runtime-config-wal.html#GUC-FULL-PAGE-WRITES -Kevin -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
