Date: Tue, 12 Mar 2013 10:33:45 +0100 From: Peter Maloney <peter.maloney@brockmann-consult.de> To: Cody Ritts <cr@caltel.com> Cc: freebsd-fs@freebsd.org Subject: Re: Aligning MBR for ZFS boot help Message-ID: <513EF679.2080402@brockmann-consult.de> In-Reply-To: <513C1629.50501@caltel.com> References: <513C1629.50501@caltel.com>
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On 2013-03-10 06:12, Cody Ritts wrote: > I think remember reading that freebsd-zfs had to be the first slice (I > cannot remember where i read that). And it apparently does not think > an offset is funny. For the gptzfsboot boot loader (and don't know which others), the bootable zfs slice has to be in the same pool as the first slice found. Or in other words, the first ZFS slice found by the bootloader must be the cache, log, or data vdev of the bootable pool. I learned this the hard way ;) www.freebsd.org/cgi/query-pr.cgi?pr=160706 eg. this would fail: slice 1 - freebsd-boot slice 2 - zfs /tank slice 3 - zfs root with /boot this would also fail: slice 1 - freebsd-boot slice 2 - zfs /tank L2ARC cache slice 3 - zfs root with /boot this would probably work (fits the rule, but I didn't test it): slice 1 - freebsd-boot slice 2 - zfs root L2ARC cache slice 3 - zfs /tank slice 4 - zfs root with /boot and this will definitely work: slice 1 - freebsd-boot slice 2 - zfs root with /boot slice 3 - zfs /tank Above examples are with gptzfsboot loader; not sure if you need a freebsd-boot for others. And FYI in possibly all BIOS machines (non-EFI), the boot slice probably needs to be before a certain sector... not sure which number, maybe 2.2TB/2.0TiB. I always just put it first. On my FreeBSD zfs machines, I put it at sector 34 which is badly aligned but means the next regular one can start at 2048, which saves me a whole megabyte! -- -------------------------------------------- Peter Maloney Brockmann Consult Max-Planck-Str. 2 21502 Geesthacht Germany Tel: +49 4152 889 300 Fax: +49 4152 889 333 E-mail: peter.maloney@brockmann-consult.de Internet: http://www.brockmann-consult.de --------------------------------------------
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