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>
next in thread | previous in thread | raw e-mail | index | archive | help
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.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?alpine.BSF.2.00.1303101749370.8481>