Date: Thu, 24 Jul 2014 22:04:48 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Dave Hayes <dave@jetcafe.org> Cc: freebsd-stable@FreeBSD.org Subject: Re: Gmirror + gpart corruption on 9.3-PRE Message-ID: <alpine.BSF.2.11.1407242120070.3624@wonkity.com> In-Reply-To: <53D1BDB2.7030906@jetcafe.org> References: <53D1BDB2.7030906@jetcafe.org>
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On Thu, 24 Jul 2014, Dave Hayes wrote: > At 9.3-PRERELEASE #0 r268066M I've been trying unsucessfuly to set up a brand > shiny new gmirror + gpt style Raid 0 mirror using the following procedure on > a disk > > gpart create -s gpt ada0 > ( shows 931G of space) > gpart add -s 96G -t freebsd-swap -l swap0 ada0 > gpart add -t freebsd-ufs -l rw0 ada0 > gpart create -s gpt ada1 > gpart add -s 96G -t freebsd-swap -l swap1 ada1 > gpart add -t freebsd-ufs -l rw1 ada1 > gmirror label swap /dev/ada0p1 /dev/ada1p1 > gmirror label rw /dev/ada0p2 /dev/ada1p2 Mirrors of GPT partitions on different disks is fine. Or rather, it's sub-optimal but will work. > gpart create -s gpt mirror/swap > gpart add -s95G -t freebsd-swap -l FBCDSWAP mirror/swap > gpart create -s gpt mirror/rw > gpart add -s833G -t freebsd-ufs -l FBCDRW mirror/rw > This consistently gives me the dreaded > > GEOM: mirror/rw: the secondary GPT table is corrupt or invalid > > just as soon as I provision the mirror/rw device. I believe that GPT tables somehow work only on the drive level. That is, the GPT partitioning created inside the mirror actually overwrites the existing one on the drive. As odd as it sounds, I think this is intentional: GPT tables are only supposed to be at the beginning and end of a physical drive. But I'm also not the one to explain it. However, the attempted GPT partitioning inside the mirrors is not needed and can be left out. > I've since upgraded this machine to the exact same 9.3 revision and it still > works fine, no corruption. Am I missing something or did something change in > between these two revisions that makes it difficult or different to set up? GPT tests got more strict at some point. Maybe the rules for GPT tables did also. For reference, here is my article on mirroring GPT disk partitions. I do not recommend it. (Consider the head contention when multiple mirrors on the same drive attempt to rebuild. Or disable automatic rebuilding, but then it's going to be unpleasant in an emergency.) http://www.wonkity.com/~wblock/docs/html/gmirror.html For drives under 2TB, use MBR and bsdlabels, as ugly as it is. The recently-rewritten Handbook procedure shows the right way to do it, including alignment: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html If the memory is available, ZFS might handle mirrored partitions better. Maybe a per-pool configurable resilvering priority, but I don't know.
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