Date: Thu, 22 Jul 2010 00:06:00 -0500 From: Scot Hetzel <swhetzel@gmail.com> To: Dan Langille <dan@langille.org> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Using GTP and glabel for ZFS arrays Message-ID: <AANLkTinAtgdKA-XwjKFMDiK0Y99uNlnN_8mxia99jl6E@mail.gmail.com> In-Reply-To: <4C47B57F.5020309@langille.org> References: <4C47B57F.5020309@langille.org>
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On Wed, Jul 21, 2010 at 10:05 PM, Dan Langille <dan@langille.org> wrote: > I hope my terminology is correct.... > > I have a ZFS array which uses raw devices. I'd rather it use glabel and > supply the GEOM devices to ZFS instead. In addition, I'll also partition > the HDD to avoid using the entire HDD: leave a little bit of space at the > start and end. > > Why use glabel? > > * So ZFS can find and use the correct HDD should the HDD device ever > get renumbered for whatever reason. e.g. /dev/da0 becomes /dev/da6 > when you move it to another controller. > > Why use partitions? > > * Primarily: two HDD of a given size, say 2TB, do not always provide > the same amount of available space. If you use a slightly smaller > partition instead of the entire physical HDD, you're much more > likely to have a happier experience when it comes time to replace an > HDD. > > * There seems to be a consensus amongst some that leaving the start and > and of your HDD empty. Give the rest to ZFS. > > Things I've read that led me to the above reasons: > > * > http://docs.freebsd.org/cgi/getmsg.cgi?fetch=399538+0+current/freebsd-stable > * > http://lists.freebsd.org/pipermail/freebsd-stable/2010-February/055008.html > * http://lists.freebsd.org/pipermail/freebsd-geom/2009-July/003620.html > > The plan for this plan, I'm going to play with just two HDD, because that's > what I have available. Let's assume these two HDD are ad0 and ad1. I am > not planning to boot from these HDD; they are for storage only. > > First, create a new GUID Partition Table partition scheme on the HDD: > > gpart create -s GPT ad0 > > > Let's see how much space we have. This output will be used to determine > SOMEVALUE in the next command. > > gpart show > > > Create a new partition within that scheme: > > gpart add -b 34 -s SOMEVALUE -t freebsd-zfs ad0 > Instead of using glabel to label the partition on a GPT disk, use this command instead: gpart add -b 34 -s SOMEVALUE -t freebsd-zfs -l disk00 ad0 You will then see a /dev/gpt/disk00. Then to create the zpool use: zpool create bigtank gpt/disk00 gpt/disk02 ... Scot
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