Date: Wed, 14 Oct 1998 23:19:25 -0500 From: Dan Nelson <dnelson@emsphone.com> To: Julian Elischer <julian@whistle.com>, "Justin T. Gibbs" <gibbs@plutotech.com> Cc: Terry Lambert <tlambert@primenet.com>, Don.Lewis@tsc.tdk.com, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: filesystem safety and SCSI disk write caching Message-ID: <19981014231925.A18446@emsphone.com> In-Reply-To: <Pine.BSF.3.95.981014105142.2872Q-100000@current1.whistle.com>; from "Julian Elischer" on Wed Oct 14 11:08:05 GMT 1998 References: <199810140518.XAA15040@pluto.plutotech.com> <Pine.BSF.3.95.981014105142.2872Q-100000@current1.whistle.com>
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In the last episode (Oct 14), Julian Elischer said:
> Hey everybody..
> look, we're in violent agreement here but haven't noticed it....
>
> 7/ to allow for this to be achieved easily, there should be an easy
> way to ensure that the write cache is turned off. Possibly as simple
> as a good example in camctl.8 .
I humbly submit the following script, to be added to /etc/security, or
periodic/weekly, /etc/rc, or wherever. It's dependant on the exact
output of "camcontrol inquiry" and "camcontrol modepage", but does the
job.
-Dan Nelson
dnelson@emsphone.com
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#! /bin/sh
echo Checking SCSI drives for write-cache:
numbad=0
# get a list of direct-access devices known to the system
units=$(camcontrol devlist | sed -n -e "/,da[0-9]*/s/.*,da\(.*\))/\1/p")
for i in $units
do
result=$(camcontrol modepage -m 8 -P 3 -u $i 2> /dev/null | grep WCE)
if [ "$result" = "WCE: 1 " ] ; then
camcontrol devlist | grep ",da${i})"
numbad=$(($numbad + 1))
fi
done
if [ $numbad -gt 0 ] ; then
s=
[ $numbad -ne 1 ] && s=s
echo "
$numbad device$s with WCE set. To reset, run
\"camcontrol modepage -e -P 3 -m 8 -u <unit>\"
where <unit> is the disk number (i.e. da0 is unit #0), and set WCE to 0."
fi
echo
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