Date: Fri, 11 Sep 2015 10:09:04 -0453.75 From: "William A. Mahaffey III" <wam@hiwaay.net> Cc: FreeBSD Questions !!!! <freebsd-questions@freebsd.org> Subject: Re: followup storage question Message-ID: <55F2ED46.6060708@hiwaay.net> In-Reply-To: <alpine.BSF.2.20.1509110821560.6365@wonkity.com> References: <55F2D086.6060509@hiwaay.net> <alpine.BSF.2.20.1509110821560.6365@wonkity.com>
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On 09/11/15 09:31, Warren Block wrote: > On Fri, 11 Sep 2015, William A. Mahaffey III wrote: > >> The Wiki page >> https://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/9.0-RELEASE illustrates >> using gnop to enforce 4K alignment of gpt partitions for subsequent >> use by ZFS. However the gpart commands also use the '-a 4k' >> arguments, aligning partitions on 4k boundaries as I understand >> things. Is the gnop command also necessary ? TIA & have a nice weekend. > > These are two separate things. gnop(8) is (was) used to force ZFS to > use a 4K block size. That just means it transfers data in multiples > of 4K, not necessarily aligned with the 4K sectors on the drive. > gpart(8)'s -a flag is used to force partitions to begin in alignment > with the 4K sectors on the drive. > Hmmmm .... OK, however if I carefully 'gpart -a 4k' the underlying partitions aligned, then wouldn't the resulting ZFS above also be aligned ? I ask because the 2nd system I will be setting up in the next few weeks will probably use a RAIDZ1 on 6-8 partitions, & I have it on pretty good authority that you want RAID5-type storage properly aligned on the underlying drives or partitions. Thanks & TIA & have a nice weekend. -- William A. Mahaffey III ---------------------------------------------------------------------- "The M1 Garand is without doubt the finest implement of war ever devised by man." -- Gen. George S. Patton Jr.
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