Scott Marlowe wrote: > Actually, it's usually the drives that lie about fsync, especially > consumer grade (and some server grade) SATA / PATA drives are known > for this. I'm still looking for any evidence of any drive that lies. Is there actually a drive which claims to support the IDE "FLUSH_CACHE_EXT" feature (IDE command 0xEA) that doesn't?!? You can see if your drive claims to - most this century do - in Linux with "hdparm -I /dev/sdX" which should show FLUSH_CACHE_EXT if the disk supports this extension. And if your disk is using a last-century IDE spec that predated that feature, I think your kernel probably told you in the startup messages that your drive is not so much lying, but obsolete and missing a feature. Software on the other hand sucks at sending these commands. Ext3 will only send the right IDE commands if the inode was touched[1]. VirtualBox doesn't send them correctly[2]. I hear LVM and MD raid can lose those events too. Since so many layers don't send the right IDE commands to flush, userspace utilities exist to send those commands[4]. I sometimes wonder if postgres should add something like that. But I still haven't found any drive that lies -- and only a couple who's firmware openly admits not to support the feature. [1] http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg272253.html [2] http://openquery.com/blog/host-flush [3] http://forum.soft32.com/linux/flush-disk-write-cache-userspace-ftopict338477.html -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
