Date: Mon, 29 Aug 2005 14:04:15 +0200 From: Matthias Buelow <mkb@incubus.de> To: Mark Kirkwood <markir@paradise.net.nz> Cc: freebsd-stable@freebsd.org, "C. Michailidis" <dinom@balstonresearch.com> Subject: Re: Sysinstall automatic filesystem size generation. Message-ID: <20050829120415.GA1462@drjekyll.mkbuelow.net> In-Reply-To: <4312ECB6.3000702@paradise.net.nz> References: <200508282330.09302.dinom@balstonresearch.com> <20050829035729.GH88693@dan.emsphone.com> <200508290225.32394.dinom@balstonresearch.com> <4312B060.4080104@paradise.net.nz> <20050829085140.GA684@drjekyll.mkbuelow.net> <4312ECB6.3000702@paradise.net.nz>
next in thread | previous in thread | raw e-mail | index | archive | help
Mark Kirkwood wrote: >>>FreeBSD's filesystems are very robust should you lose power. >>This sentence is completely bogus (or at best: wishful thinking) >>and should be deleted. >It's probably correct if you have hw.ata.wc=0 (and are using IDE drives >obviously). I'd like to stress the "probably". I've already seen unrepairable filesystem corruption with softupdates enabled in the past with "good" scsi disks at power loss. Furthermore, disabling the write-back cache in a typical consumer (read: typical PC workstation) environment today, with large IDE/SATA drives, is unrealistic because of the severe performance degradation, and might even be counter-indicated due to the increased wear&tear on the disk, which might significantly reduce the disk's lifetime. Softupdates works only in an idealized environment that doesn't match against reality. In addition, with softupdates there seems to be a much higher probability of losing files, as I have observed.. that is, getting them zero-truncated, or even deleted (which shouldn't happen in that scenario, I'm sure I've seen the results of a bug), than without. Do I still use softupdates? Yes, because of the performance benefit, but I don't treat it as much different than completely asynchronous operation, with the only difference that it's a slightly more resilient in case of a kernel crash (vs. a power outage) and I make frequent backups. mkb.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050829120415.GA1462>