On 17 Mar 2013, at 04:30, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Oleg Alexeev <oalexeev@xxxxxxxxx> writes: >> * it is varchar columns, 256 and 32 symbols length >> * encoding, collation and ctype: UTF8, en_US.utf8, en_US.utf8 >> * autovacuum, fsync off, full_page_writes = on, wal_writer_delay = 500ms, >> commit_delay = 100, commit_siblings = 10, checkpoint_timeout = 20min, >> checkpoint_completion_target = 0.7 >> * postgres 9.2.3 installed via yum repository for version 9.2 >> * 64 bit Centos 6, installed and updated from yum repository > > fsync off? Have you had any power failures or other system crashes? > ext4 is *way* more prone than ext3 was to corrupt data when fsync is > disabled, because it caches and reorders writes much more aggressively. > >> Database located on software md raid 1 based on two SSD disks array. Ext4 >> filesystem. Database is master node. > > Meh. I quote from the RHEL6 documentation (Storage Administration > Guide, Chapter 20: Solid-State Disk Deployment Guidelines): > >> Red Hat also warns that software RAID levels 1, 4, 5, and 6 are not >> recommended for use on SSDs. > > https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newmds-ssdtuning.html > > The part of the docs I'm looking at only asserts that performance is > bad, but considering that it's a deprecated combination, it may well be > that there are data-loss bugs in there. I'd certainly suggest making > sure you are on a *recent* kernel. If that doesn't help, reconsider > your filesystem choices. > Yeah, I don't think I'd consider using software raid for SSDs any time a good idea -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
