Date: Sat, 21 Jan 2012 21:57:52 +0200 From: Daniel Kalchev <daniel@digsys.bg> To: Willem Jan Withagen <wjw@digiware.nl> Cc: Alexander Leidinger <Alexander@Leidinger.net>, fs@freebsd.org Subject: Re: Question about ZFS with log and cache on SSD with GPT Message-ID: <AD03CC71-8142-4C2B-9FF5-F548EF377464@digsys.bg> In-Reply-To: <4F1B0177.8080909@digiware.nl> References: <4F193D90.9020703@digiware.nl> <20120121162906.0000518c@unknown> <4F1B0177.8080909@digiware.nl>
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On Jan 21, 2012, at 8:18 PM, Willem Jan Withagen wrote: > On 21-1-2012 16:29, Alexander Leidinger wrote: >>> > >> See >> http://www.leidinger.net/blog/2011/05/03/another-root-on-zfs-howto-optimized-for-4k-sector-drives/ >> for a description how to align to 4k sectors. I do not know if the main >> devices of the pool need to be setup with an emulated 4k size (the gnop >> part in my description) or not, but I would assume all disks in the >> pool needs to be setup with the temporary gnop setup. > > Well one way of resetting up the harddisks would be to remove them from > the mirror each in turn. Repartion, and then rebuild the mirror, hoping > that that would work, since I need some extra space to move the > partitions up. :( With ZFS, the 'alignment' is on per-vdev -- therefore you will need to recreate the mirror vdevs again using gnop to make them 4k aligned. Only one disk in a vdev needs to be 'gnop-ed' to 4k sectors because ZFS uses the largest sector size from all devices in a vdev as the vdev 'ashift' at creation time. Daniel
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