Date: Tue, 13 May 2008 20:36:59 -0400 From: mcdouga9 <mcdouga9@egr.msu.edu> To: hartzell@alerce.com Cc: freebsd-stable@freebsd.org Subject: Re: good/best practices for gmirror and gjournal on a pair of disks? Message-ID: <482A342B.1020606@egr.msu.edu> In-Reply-To: <18474.3218.145536.664367@almost.alerce.com> References: <18473.48984.31132.91673@almost.alerce.com> <4829FBC8.5040101@egr.msu.edu> <18474.3218.145536.664367@almost.alerce.com>
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George Hartzell wrote: > Adam McDougall writes: > > George Hartzell wrote: > > >[...] > > > - I've read in the gjournal man page that when it is "... configured > > > on top of gmirror(8) or graid3(8) providers, it also keeps them in > > > a consistent state..." I've been trying to figure out if this > > > simply falls out of how gjournal works or if there's explicity > > > collusion with gmirror/graid3 but can't come up with a > > > satisfactory explanation. Can someone walk me through it? > > > > > > Since I'm only gjournal'ing a portion of the underlying gmirror > > > device I assume that I don't get this benefit? > > >[...] > > [...] > > I decided to journal /usr /var /tmp and leave / as a standard UFS > > partition because it is so small, fsck doesn't take long anyway and > > hopefully doesn't get written to enough to cause damage by an abrupt > > reboot. Because I'm not journaling the root partition, I chose to > > ignore the possibility of gjournal marking the mirror clean. Sudden > > reboots don't happen enough on servers for me to care. And all my > > servers got abruptly rebooted this sunday and they all came up fine :) > > [...] > > So you're confirming my belief that setting up gjournal on a > bsdlabel'ed partition of a gmirror does *not* provide the consistency > guarantee and that I should leave autosynchronization enabled. Right? > > g. > I forgot to address that. I think to gain that, you have to (re)label the mirror using -F (see man gmirror). I believe without using -F, the mirrors will still be synced (but probably don't need to). Otherwise, look for initial mail list announcements (freebsd-current?) of gjournal which may explain.
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