Date: Tue, 3 Dec 2013 18:37:00 +0100 From: Julien Cigar <jcigar@ulb.ac.be> To: Warren Block <wblock@wonkity.com> Cc: "Mike." <the.lists@mgm51.com>, freebsd-questions@freebsd.org Subject: Re: gmirror, gpart and MBR vs GPT in the Handbook Message-ID: <20131203173700.GD86280@mordor.lan> In-Reply-To: <alpine.BSF.2.00.1312030920040.23862@wonkity.com> References: <201311301303210813.05DE187E@smtp.24cl.home> <alpine.BSF.2.00.1311301352140.99113@wonkity.com> <201312011121580096.005D00FB@smtp.24cl.home> <20131202103122.GN66981@mordor.lan> <alpine.BSF.2.00.1312020847510.14007@wonkity.com> <20131203092604.GA86280@mordor.lan> <alpine.BSF.2.00.1312030920040.23862@wonkity.com>
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On Tue, Dec 03, 2013 at 09:27:12AM -0700, Warren Block wrote: > On Tue, 3 Dec 2013, Julien Cigar wrote: > > > On Mon, Dec 02, 2013 at 08:56:13AM -0700, Warren Block wrote: > >> On Mon, 2 Dec 2013, Julien Cigar wrote: > >> > >>> If you want to use GPT with gmirror you may want to mirror each > >>> partition instead of the whole disk. > >>> > >>> For example on my box I have the following: https://dpaste.de/Rb3S > >> > >> There are a couple of potential problems with that. The big one is when > >> a disk fails and is replaced. If you're not careful, the rebuild of all > >> those mirrored partitions will start at the same time. Head contention > >> will bring that to a near-standstill. It also puts a heavy load on the > >> drive that still works. Hopefully it is not the same model and age as > >> the one that failed, or its "warranty timer" may also be close to > >> expiring. > > > > That's true, I turned off autosynchronization of stale components to > > avoid this kind of bad scenario .. > > > >> > >> A less-serious problem is that only the partitions are mirrored. That > >> leaves out metadata like the partition tables and bootcode, but those > >> typically do not change very often and might not be a problem. The > >> admin has to remember to manually install such things on a new > >> replacement disk, though. > > > > It's just a matter of gpart backup / gpart restore, right ? > > That will get the partition tables but not the bootcode or PMBR. A > failed disk could then leave a mirror which has all the data but is > unbootable. ok, so I've to be sure that: $> gpart bootcode -b /boot/pmbr -p gptboot -i 1 adaX is executed for each disk involved in the mirror, right ..? > > At some point, we'll have to address the conflict between gmirror and > GPT. ZFS mirrors can replace gmirror in some situations, but not all. > _______________________________________________ > 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" -- No trees were killed in the creation of this message. However, many electrons were terribly inconvenienced.
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