Date: Thu, 19 Jan 2006 06:24:50 -0600 From: "Larry Rosenman" <ler@lerctr.org> To: "'Gavin Atkinson'" <gavin.atkinson@ury.york.ac.uk> Cc: freebsd-stable@freebsd.org Subject: RE: Gmirror'd SWAP: no dump? Message-ID: <00c401c61cf3$581cc930$68c8a8c0@lerctr.org> In-Reply-To: <1137672877.89997.8.camel@buffy.york.ac.uk>
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Gavin Atkinson wrote: > On Thu, 2006-01-19 at 05:49 -0600, Larry Rosenman wrote: >> Igor Robul wrote: >>> On Wed, Jan 18, 2006 at 12:44:27PM -0600, Larry Rosenman wrote: >>>> Are there any plans to support dumping to a gmirror'd swapfile? >>> Dumping occurs when kernel is in "bad condition", so GEOM can not be >>> safe used (for example panic in GEOM code). >>> >>> Check archives for last month of 2005 for longer explanation. >> >> I was afraid of that. What's the recommendation for how to Set up a >> 2-disk system with mirroring then? >> >> All the HOWTO's I've seen have the entire disk mirrored, including >> all the pieces. >> >> My current setup is 3 BSD partitions in 1 FDISK slice. With the >> entire disk (da0/da1) mirrored. >> >> How can I set it up to allow dumps? > > If you look at the mirror status, you'll see each disk is assigned a > priority. > > In theory, "The component with the biggest priority is used [...] as > a master component when resynchronization is needed, e.g. after a > power failure when the device was open for writing." (gmirror(8)). > Therefore, if you set dumps to /dev/da0s1b (or whichever swap > partition is on the disk with the biggest priority), the machine can > dump to the disk directly, and will end up resyncing to the other > disk on reboot (which it would have had to do anyway due to the > panic), and your dump will be doubly safe. The problem with this idea is the fact that the da0s1b device is NOT available: $ ls -l /dev/da?s1? ls: /dev/da?s1?: No such file or directory $ -- Larry Rosenman http://www.lerctr.org/~ler Phone: +1 512-248-2683 E-Mail: ler@lerctr.org US Mail: 430 Valona Loop, Round Rock, TX 78681-3683 US
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