From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Maryshev <boris.maroshev@itcollege.ee>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] Seagate Barracuda 7200.7 write cache?
Date: Tue, 13 Jul 2004 11:48:29 +0300
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On Tuesday 13 July 2004 11:25, David Eckhardt wrote:
> Am I being overly paranoid?
>
> http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda7200.7.pdf
> is the "data sheet" for the SATA version of the Seagate Barracuda.
>
> Section 4.3.2 ("Set Features command") on logical page 31 (physical
> page 41) seems to indicate that the drive defaults to handling sector
> writes via a write-back RAM cache, which the host OS can disable.
>
> Is it just me or is this a very bad default except (maybe) for
> battery-backed systems?  Is this a standard thing in IDE disks
> (either the feature number or the default setting), something
> Plan 9 should watch out for, nothing for me to worry my pretty
> little head about, ...?
It isn't enabled by default on all IDE HDDs AFAIK. Some recommend to enable
it, because you get increased throughput, but some UNIX vendors do not, as
you can get filesystem corruption in case of power failure. Journalling
doesn't help here either IIRC.
>
> Dave Eckhardt
Boris Maryshev
--
A banker is a fellow who lends you his umbrella when the sun is shining
and wants it back the minute it begins to rain.
		-- Mark Twain