Date: Thu, 18 Nov 2004 14:05:51 GMT From: Arne Wörner <arne_woerner@yahoo.com> To: freebsd-gnats-submit@FreeBSD.org Subject: i386/74074: hw.ata.wc=0 / but write cache still enabled Message-ID: <200411181405.iAIE5pqa053338@www.freebsd.org> Resent-Message-ID: <200411181410.iAIEARVE028663@freefall.freebsd.org>
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>Number: 74074 >Category: i386 >Synopsis: hw.ata.wc=0 / but write cache still enabled >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-i386 >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Thu Nov 18 14:10:27 GMT 2004 >Closed-Date: >Last-Modified: >Originator: Arne Wörner >Release: R5.3 >Organization: >Environment: FreeBSD neo.riddick.homeunix.org. 5.3-RELEASE FreeBSD 5.3-RELEASE #0: Thu Nov 11 17:27:53 UTC 2004 aw@neo.riddick.homeunix.org.:/usr/obj/usr/src/sys/RIDDICK i386 >Description: I wanted to turn of ATA disc write caching (by setting hw.ata.wc to zero): but after a boot after power on atacontrol cap 0 0 still says, that the write cache feature is enabled: write cache yes yes while sysctl says, that hw.ata.wc is 0: # sysctl hw.ata.wc hw.ata.wc: 0 I think this is a bug, that can be security relevant in the case of a power failure or system crash (at least if one is using a filesystem with soft updates enabled). After a reboot (warm) the write cache is sometimes disabled but sometimes enabled... :-( >How-To-Repeat: 1. shutdown the box 2. turn off power 3. turn on power 4. look at hw.ata.wc 5. look ata atacontrol's output >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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