Date: Wed, 30 Jan 2013 18:31:38 +0400 From: Artem Kuchin <matrix@itlegion.ru> To: Warren Block <wblock@wonkity.com> Cc: freebsd-questions@freebsd.org Subject: Re: Software raid VS hardware raid Message-ID: <51092ECA.6070808@itlegion.ru> In-Reply-To: <alpine.BSF.2.00.1301300635130.37822@wonkity.com> References: <5106E301.4070707@itlegion.ru> <ke7v7a$r0d$1@ger.gmane.org> <5107A500.4030902@itlegion.ru> <alpine.BSF.2.00.1301290749460.27370@wonkity.com> <5107FC3C.4030701@itlegion.ru> <alpine.BSF.2.00.1301291353570.30931@wonkity.com> <51090721.2010606@itlegion.ru> <alpine.BSF.2.00.1301300635130.37822@wonkity.com>
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30.01.2013 18:06, Warren Block: > On Wed, 30 Jan 2013, Artem Kuchin wrote: > >> >> 30.01.2013 1:01, Warren Block: >>> On Tue, 29 Jan 2013, Artem Kuchin wrote: >>> >>>> >>>> 29.01.2013 18:57, Warren Block: >>>>> On Tue, 29 Jan 2013, Artem Kuchin wrote: >>>>> >>>>> The Handbook chapter on gmirror talks about the problems with GPT >>>>> and GEOM metadata. In short: right now, they conflict. It's >>>>> possible to mirror GPT partitions, but be aware that if you mirror >>>>> more than one partition on a drive, a rebuild after replacing a >>>>> drive could thrash the heads as mirrors are rebuilt simultaneously. >>>>> >>>>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html >>>>> >>>> >>>> So, >>>> gmirror+GPT=conflict on last sector >>>> GPT+gmirror = hardrive head kill >>>> >>>> nice... >>>> >>>> So, for no more than 2TB disks the best way to go is GMIRROR of the >>>> drive +PARTITION on top of it? >>> >>> GPT partitions should work, just limit it to one mirrored partition >>> per drive. >> >> Please, clarify what you mean here. > > If only one GPT partition on a drive is mirrored with another GPT > partition on another drive, head contention never comes up. There is > only one mirror. > > It does nearly eliminate the usefulness of GPT partitioning. > Um... and how can i do that if i have a simple mirror with two drives and want to mirror everything on them? As i understand i will have at least bootable, swap and ufs parttions on those drives, that is 3 partitions at least. Artem
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