Date: Tue, 13 Oct 2009 12:13:53 +0100 From: Vincent Hoffman <vince@unsane.co.uk> To: krad <kraduk@googlemail.com> Cc: Daniel Bye <freebsd-questions@slightlystrange.org>, freebsd-questions@freebsd.org Subject: Re: gmirror, gjournal and glabel - which order? Message-ID: <4AD460F1.7020405@unsane.co.uk> In-Reply-To: <d36406630910130137y46e8960r6b681242624b558a@mail.gmail.com> References: <20091012211339.GA12688@torus.slightlystrange.org> <4AD3A8EE.8020708@otenet.gr> <20091013002919.GB12688@torus.slightlystrange.org> <d36406630910130137y46e8960r6b681242624b558a@mail.gmail.com>
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krad wrote: > 2009/10/13 Daniel Bye <freebsd-questions@slightlystrange.org> > > >> On Tue, Oct 13, 2009 at 01:08:46AM +0300, Manolis Kiagias wrote: >> >>> Daniel Bye wrote: >>> >>>> Hi all, >>>> >>>> I'm having a hard time trying to work out which order I should set up >>>> gmirror, glabel and gjournal on a new system. I want to journal my >>>> /home partition, label all the partitions for ease of reference, and >>>> use gmirror to save me in the event a disk goes bad. I am struggling >>>> to fit the pieces together conceptually in my mind. I understand the >>>> processes involved in setting each part separately - my problem is in >>>> trying to build this up in the right order so that it all makes sense. >>>> >>>> So far, I have labelled the primary drive and set up the journal. I >>>> >> have >> >>>> edited fstab to reflect the labels and journalled file system on /home. >>>> If I now build a mirror, don't I need to alter fstab to mount that and >>>> not the stuff in /dev/label? In which case, I guess I need to build the >>>> mirror first, and then set up labels and journals? >>>> >>>> I'm going round and round in circles here and none of the stuff I've >>>> read on the web enlightens me... :-/ >>>> >>>> Any insights or suggestions would be taken as a great kindness! >>>> >>>> Dan >>>> >>>> >>>> >>> When not mirroring, I first create the journals and then label the >>> resulting adxxxx.journal devices >>> In case you are doing a gmirror device, you would not really need the >>> separate label step - the gm device name won't change and gmirror is not >>> affected if the device names of the individual disks change (the disks >>> are marked as part of a mirror and scanned at startup). >>> When you are creating the composite gmirror device you are effectively >>> labeling it anyway i.e. gmirror label gm0... >>> Now if you follow the usual tutorials found in the web you would be >>> using gm0 / gm1 but you actually name it any way you wish. >>> If you really need to label the separate gmirrored partitions, do it >>> after setting up the mirror. >>> >>> Concerning the order of journals and mirroring, I create the journals >>> first, then mirror the result. This has always worked fine for me. >>> >> Thanks much, Manoli. After posting, I came to more or less the same >> conclusion, but it's good to get confirmation from someone who clearly >> knows more about this stuff than I do! >> >> I'd still be interested to hear what others think/do. >> >> As ever, thanks for your time. >> >> Dan >> >> -- >> Daniel Bye >> _ >> ASCII ribbon campaign ( ) >> - against HTML, vCards and X >> - proprietary attachments in e-mail / \ >> >> > > > I've always gmirrored 1st, then created the gjournal then newfs the journal > device with the -L and -J flags to label it. I'm not sure if this is correct > but ufs2 has hooks into gjournal, and if the journal class inst directly > below the ufs layer these hooks might not work correctly. > I've always done it this way too (mirror then journal,) both for the reason given and because of the following from the gjournal(8) manpage: When gjournal is configured on top of gmirror(8) or graid3(8) providers, it also keeps them in a consistent state, thus automatic synchronization on power failure or system crash may be disabled on those providers. Vince > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" >
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