Date: Wed, 19 Nov 2014 15:50:46 +0100 From: Mark Martinec <Mark.Martinec+freebsd@ijs.si> To: freebsd-stable@freebsd.org Subject: Re: 10.1 fresh install and 4k alignment Message-ID: <27d8222a2b617ac515c38a0023151320@mailbox.ijs.si> In-Reply-To: <EB886DA7-5935-41D2-B462-943CA0B30548@punkt.de> References: <A2328132-EC43-4E27-8D01-A4D774634598@punkt.de> <ead753e90b2b74b169af2fb04c525c9e@mailbox.ijs.si> <EB886DA7-5935-41D2-B462-943CA0B30548@punkt.de>
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> None of the start sector numbers is a multiple of 8, neither are the > end sectors a multiple of 8 minus 1. > > So the pool uses a 4k block size but it starts on an odd multiple of 2k > on the platter - do I see this correctly? > [...] > Is this a bug in the installer? Will I still have to layout the disks > manually if I want 4k alignment? What's a good offset for the first > partition in this case? Anything bigger than 34 that's a multiple of > 8 - 40 or 64? >> "GPT partitions not 4k aligned by 10.1-RC1 installer" >> >> https://lists.freebsd.org/pipermail/freebsd-stable/2014-October/080509.html I consider a sensible alignment nowadays to be '-a 1m' for any GPT partition, including freebsd-boot. If one is very short on space and not on an SSD, one may save 0.5 MB by aligning freebsd-boot on -a 512k and everything else on '-a 1m': gpart add -t freebsd-boot -a 1m -s 512k -i 1 ... gpart add -t freebsd-swap -a 1m -i 2 ... ... or: gpart add -t freebsd-boot -a 512k -s 512k -i 1 ... gpart add -t freebsd-swap -a 1m -i 2 ... ... Mark
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