Date: Tue, 23 Jan 2007 08:29:25 -0600 From: James Riendeau <jtriende@wisc.edu> To: Jonathan Horne <freebsd@dfwlp.com> Cc: freebsd-questions@freebsd.org Subject: Re: gmirror setup Message-ID: <E4D53FE6-D1DA-4768-980A-E885BF2DC0D5@wisc.edu>
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> i just set up my first gmirror raid1, and... it was really simple. > too > simple. "ok... what did i skip or do wrong?", was my first thought. > > i follow the doc from onlamp.com: > > http://www.onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html?page=1 > > i did have one giant deviation tho, and im wondering if it really > makes a > difference. the article depicts creating the gmirror immediately > following > initial operating system install, but i did my example on a fully > functioning > system. other than that, i have 2 identical disks, and things seem > to be > working: > > castor# gmirror status > Name Status Components > mirror/gm0 DEGRADED ad0 > ad1 (33%) > > im sure im seeing less than the best performance since im using but > a single > > ide channel, but other than that, is it feasible to insert an > identical > disk, > and setup the gmirror at anytime a freebsd'er likes? > > also, the doc didnt mention it, but if you do use to differing disk > sizes, > obviously the smaller one should be ad0? and other than that, is > there any > difference in setting up gmirror if the second disk is larger? > > cheers, > jonathan The surest way to test your raid is to unplug the IDE cable to one drive while the system is running and see if it still works. Plug it back in and rebuild the drive. Do the same for the other drive. Setting up gmirror on a new system is straight forward; trying to set it up on a system that can't be taken down for a day can be a major headache. I would like to stress that a mirrored RAID setup is no substitute for a solid backup plan. If there is a data error, gmirror will faithfully replicate that error on the other drive. You may not find out that a drive has failed until both drives fail especially if you're not keeping a close eye on your daily reports, so a backup is essential. James Riendeau MMI Computer Support Technician 1300 University Ave Rm. 436, Dept. of MedMicro Madison, WI 53706
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