Date: Fri, 23 Jul 2010 22:32:07 -0400 From: Dan Langille <dan@langille.org> To: freebsd-stable@freebsd.org Subject: Re: Using GTP and glabel for ZFS arrays Message-ID: <4C4A50A7.2090305@langille.org> In-Reply-To: <AANLkTi=fMR1pQj11qCqMWwCM9nsovsm_PVh7%2BJeWF0ED@mail.gmail.com> References: <4C47B57F.5020309@langille.org> <4C48E695.6030602@langille.org> <718046944.20100723032259@nitronet.pl> <4C4A42D5.7080805@langille.org> <AANLkTi=fMR1pQj11qCqMWwCM9nsovsm_PVh7%2BJeWF0ED@mail.gmail.com>
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On 7/23/2010 10:25 PM, Freddie Cash wrote: > On Fri, Jul 23, 2010 at 6:33 PM, Dan Langille<dan@langille.org> wrote: >> Pawell and I had an online chat about part of my strategy. To be clear: >> >> I have a 5x2TB raidz1 array. >> >> I have 2x2TB empty HDD >> >> My goal was to go to raidz2 by: >> - copy data to empty HDD >> - redo the zpool to be raidz2 >> - copy back the data >> - add in the two previously empty HDD to the zpol >> >> I now understand that after a raidz array has been created, you can't add a >> new HDD to it. I'd like to, but it sounds like you cannot. >> >> "It is not possible to add a disk as a column to a RAID-Z, RAID-Z2, or >> RAID-Z3 vdev." http://en.wikipedia.org/wiki/ZFS#Limitations >> >> So, it seems I have a 5-HDD zpool and it's going to stay that way. > > You can fake it out by using sparse files for members of the new > raidz2 vdev (when creating the vdev), then offline the file-based > members so that you are running a degraded pool, copy the data to the > pool, then replace the file-based members with physical harddrives. So I'm creating a 7 drive pool, with 5 real drives members and two file-based members. > I've posted a theoretical method for doing so here: > http://forums.freebsd.org/showpost.php?p=93889&postcount=7 > > It's theoretical as I have not investigated how to create sparse files > on FreeBSD, nor have I done this. It's based on several posts to the > zfs-discuss mailing list where several people have done this on > OpenSolaris. I see no downside. There is no risk that "it won't work and I'll lose all the data". -- Dan Langille - http://langille.org/
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