Date: Sun, 10 Mar 2013 17:59:17 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Adam Nowacki <nowakpl@platinum.linux.pl> Cc: freebsd-fs@freebsd.org Subject: Re: Aligning MBR for ZFS boot help Message-ID: <alpine.BSF.2.00.1303101749370.8481@wonkity.com> In-Reply-To: <513D0E90.5090105@platinum.linux.pl> References: <513C1629.50501@caltel.com> <513D0E90.5090105@platinum.linux.pl>
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On Sun, 10 Mar 2013, Adam Nowacki wrote: > I don't think zfsboot is aware of BSD disklabel (offsets other than 0 won't > boot). Is there any reason you are using BSD disklabel and not two partition > MBR? MBR slices created on FreeBSD are forced to CHS alignment, pretty much always misaligned for 4K-block hard drives or SSDs. > I also don't think there is any merit in aligning to 1MiB. Most ZFS IOs will > be aligned to sector size (ashift). Unless ZFS pool is created with higher > ashift then the 63 sector offset is as good as any. If the drive has 4K sectors, that will be misaligned, potentially cutting speeds drastically even if ashift is 9.home | help
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