Date: Thu, 19 Oct 1995 11:17:51 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: gary@palmer.demon.co.uk (Gary Palmer) Cc: luigi@labinfo.iet.unipi.it, questions@freebsd.org Subject: Re: SCSI HD recommendation Message-ID: <199510191817.LAA02975@phaeton.artisoft.com> In-Reply-To: <694.814102252@palmer.demon.co.uk> from "Gary Palmer" at Oct 19, 95 12:30:52 pm
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> Luigi Rizzo stands accused of writing in message ID > <199510191023.LAA02700@labinfo.iet.unipi.it>: > >I have to buy a large (>= 4GB) SCSI HD, and have been offered > >the following: > > > Fujitsu 4.3GB > > Micropolis 4.3GB > > Micropolis 4.3GB AV (?) > > Micropolis 9.1GB > > Micropolis 9.1GB AV (?) > > >(don't know what the "AV" stands for, those "AV" models are about 5% cheaper > >than the other ones). > > ERRR??? AV means ``Audio/Video'' (or something), and they do strange > things (probably have a whacking great big on-board cache) so that > when the drive auto-recalibrates it doesn't slow down any transfers > too much, so that digital audio/video applications won't notice the > disk going off and doing housekeeping. > > Hence, they are normally (at least) 5% >>MORE<< than the ordinary > drives. Not all AV implementations use cache. Most, in fact, skip the thermal recalibration, reducing the MTBF for the drive. As a matter of fact, I don't know of an AV drive that uses a cache to prevent thermal recalibration delays instead of skipping the recalibration entirely. > >Any recommendation on which of the above are known for good/bad > >performance/reliability ? In my experience, AV drives are less reliable, a trade-off for real-time streaming response -- not a typical concern for your average non-AV user. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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