Date: Sun, 10 Mar 2013 12:47:53 -0700 From: Cody Ritts <cr@caltel.com> To: freebsd-fs@freebsd.org Subject: Re: Aligning MBR for ZFS boot help Message-ID: <513CE369.4030303@caltel.com> In-Reply-To: <alpine.BSF.2.00.1303101326530.7218@wonkity.com> References: <513C1629.50501@caltel.com> <alpine.BSF.2.00.1303101006490.5989@wonkity.com> <513CD9AB.5080903@caltel.com> <alpine.BSF.2.00.1303101326530.7218@wonkity.com>
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Yeah, just for clarity: > root@lightning# gpart show da0s1 > => 0 39068064 da0s1 BSD (18G) > 0 32 - free - (16k) > 32 39067648 1 freebsd-zfs (18G) > 39067680 384 - free - (192k) and > dd if=/boot/zfsboot of=/dev/da0s1 count=1 > dd if=/boot/zfsboot of=/dev/da0s1a skip=1 seek=1024 will not boot. and will result in: > zfsboot: No ZFS Pools located, can't boot The freebsd-zfs slice cannot have an offset. I tried it several different ways first, since it was the easiest to align, and as soon as I added that offset, the boot strap process would break. Thanks Cody On 3/10/13 12:34 PM, Warren Block wrote: > On Sun, 10 Mar 2013, Cody Ritts wrote: > >> So, aligning to 63MB was still tricky. I found your thread, but I >> could not find step by step how to calculate the offset. > > Here is the procedure I had in mind: > > # gpart create -s mbr da0 > da0 created > root@lightning# gpart add -t freebsd -b 2016 da0 > da0s1 added > # gpart show da0 > => 63 39070017 da0 MBR (18G) > 63 1953 - free - (976k) > 2016 39068064 1 freebsd (18G) > > # gpart create -s bsd da0s1 > da0s1 created > # gpart add -t freebsd-zfs -a 1m da0s1 > da0s1a added > root@lightning# gpart show da0s1 > => 0 39068064 da0s1 BSD (18G) > 0 32 - free - (16k) > 32 39067648 1 freebsd-zfs (18G) > 39067680 384 - free - (192k) > > The first slice starts at the last CHS-aligned block before 1M, or 2016. > Misaligned, but not a problem because nothing will be reading from that > location. > > The freebsd-zfs partition is created, letting gpart align it to 1M. > gpart starts the partition at an offset of 32, making it the 1M-aligned > block 2048 of the disk. > > gpart should also be able to install the bootcode correctly, but I have > not tried it for MBR and ZFS. >
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