Date: Tue, 19 Jul 2011 15:00:26 -0700 From: Chuck Swiger <cswiger@mac.com> To: Peter Jeremy <peterjeremy@acm.org> Cc: "freebsd-stable@freebsd.org Stable" <freebsd-stable@freebsd.org> Subject: Re: Status of support for 4KB disk sectors Message-ID: <02D367A5-CA74-4E8A-BE3E-F81485B287A7@mac.com> In-Reply-To: <20110719211039.GA16085@server.vk2pj.dyndns.org> References: <CAN6yY1uaUqk2ifiNViJyMFJWf60a4DmCiVs3Z=--_TjtzseABQ@mail.gmail.com> <20110718234124.GA5626@icarus.home.lan> <CAN6yY1uaEwoEhEuoTNPqzywRaCPEvcLY-ddyFRUV00FcBDU1BA@mail.gmail.com> <E8F5CB22-21D5-4AF9-A690-1DB99D31F4CC@mac.com> <20110719211039.GA16085@server.vk2pj.dyndns.org>
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On Jul 19, 2011, at 2:10 PM, Peter Jeremy wrote: > On 2011-Jul-19 10:54:38 -0700, Chuck Swiger <cswiger@mac.com> wrote: >> Unix operating >> systems like SunOS 3 and NEXTSTEP would happily run with a DEV_BSIZE >> of 1024 or larger-- they'd boot fine off of optical media using >> 2048-byte sectors, > > Actually, Sun used customised CD-ROM drives that faked 512-byte > sectors to work around their lack of support for anything else. Hmm-- my brain could be fuzzy about things twenty-plus years ago. But I remember booting a Sun3_35 or _60 from a non-Sun or Sun OEM'ed SCSI CD-ROM drive, probably a Plextor? >> some of the early 1990's era SCSI hard drives supported low-level reformatting to a different sector size like 1024 or 2048 bytes. > > Did anyone actually do this? I wanted to but was warned against > it by the local OS rep (this was a Motorola SVR2). Worked fine with 250MB Seagate ST1280 drives, and also a a 1GB Micropolis 2112. It made a decent gain to available disk capacity (about 10-15%), and a smaller improvement to performance (about 5% IIRC). It wouldn't work with drives using a dedicated embedded servo for sector positioning (ie, Quantum and DEC), but other vendors like Seagate used a normal platter surface for servo positioning, and you could reformat it with a different sector size. Regards, -- -Chuck
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