Date: Wed, 12 Oct 2011 10:43:23 -0700 From: Artem Belevich <art@freebsd.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-fs@freebsd.org Subject: Re: AF (4096 byte sector) drives: Can you mix/match in a ZFS pool? Message-ID: <CAFqOu6jBqkOEuEvS6_NfwqE%2B9L%2Bm-QumcOUbQn8Xy1vCfgJPOA@mail.gmail.com> In-Reply-To: <20111012172912.GA27013@icarus.home.lan> References: <4E95AE08.7030105@lerctr.org> <20111012155938.GA24649@icarus.home.lan> <4E95C546.70904@digsys.bg> <20111012172912.GA27013@icarus.home.lan>
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On Wed, Oct 12, 2011 at 10:29 AM, Jeremy Chadwick <freebsd@jdc.parodius.com> wrote: > How does ZFS determine this? =A0I was under the impression that this > behaviour was determined by (or "assisted by") ashift. > > Surely ZFS cannot ask the underlying storage provider (e.g. GEOM on > FreeBSD) what logical vs. physical sector size to use (e.g. for SATA > what's returned in the ATA IDENTIFY payload), because on SSDs such as > Intel SSDs *both* of those sizes are reported as 512 bytes (camcontrol > identify confirms). In r222520 mav@ added ADA_Q_4K quirks for bunch of Hitachi, Seagate and WD drives so that geom_disk will be aware of 4K sectors at least for some disks. I'm not sure whether ZFS picks it up, though. --Artem
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