Date: Thu, 31 Aug 2006 13:17:50 -0400 From: "David Robillard" <david.robillard@gmail.com> To: "Jonathan McKeown" <jonathan@hst.org.za> Cc: FreeBSD Questions Mailing List <freebsd-questions@freebsd.org> Subject: Re: Mirroring: gvinum or gmirror? Message-ID: <226ae0c60608311017j1a4bea9cg6dbaa12414d74716@mail.gmail.com>
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> I'm setting up a remote server with two identical hard drives, running > FreeBSD-6.1. I want to set the drives up as a mirror for data redundancy. I > also want to be able to break the mirror when I need to update the OS or > installed software, so that if anything goes wrong with the update on one > drive I can boot back to the other one, or if all is well, re-establish the > mirror and synchronise to the updated system. I have serial console access > including BIOS console redirection. > > Based on web and Usenet/mailing list searches, gmirror looks more > straightforward for this simple case, gvinum more flexible but poorly > documented, and the most recent comments I can find (still all 6+ months ago) > seem to suggest that gvinum hasn't completely stabilised for production yet. > > Is this a fair assessment? Are there any factors I've missed? Which solution > is likely to suit the situation better? > > Jonathan Hello Jonathan, I run gmirror on all machines which don't have a hardware RAID controller. I've had drive failures in the past and gmirror handled it very well. It's now a lot better under 6.1 then 5.x (mostly concerning the kernel dump area and the swapoff option in rc.conf(5)). Take a look at Ralf S. Engelschall's documentation on the subject: http://people.freebsd.org/~rse/mirror/ Bonus Tip of the day! If you ever have two disk drives which are not identical, such as these: ad0: 4112MB <WDC AC24300L 09.09M08> at ata0-master UDMA33 ad3: 4028MB <Maxtor 84320D4 NAVXAA21> at ata1-slave UDMA33 Then make sure you install FreeBSD on the bigger one (i.e. here that would be ad0) then setup gmirror. If you do the oposite, you will have a "Consumers too small" error when you try to bring the mirror together. Finally, keep in mind that gmirror is only good for RAID 1. If you need more powerfull volume management tools such as Veritas Volume Manager or Sun DiskSuite, then you need gvinum. Regards, David -- David Robillard UNIX systems administrator & Oracle DBA CISSP, RHCE & Sun Certified Security Administrator Montreal: +1 514 966 0122
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