From owner-freebsd-stable Sat Aug 31 7:25:59 2002 Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 648AD37B400 for ; Sat, 31 Aug 2002 07:25:53 -0700 (PDT) Received: from c18070.belrs1.nsw.optusnet.com.au (c18070.belrs1.nsw.optusnet.com.au [210.49.78.171]) by mx1.FreeBSD.org (Postfix) with SMTP id 42B8743E3B for ; Sat, 31 Aug 2002 07:25:52 -0700 (PDT) (envelope-from ajmawer@optusnet.com.au) Received: (qmail 62201 invoked from network); 31 Aug 2002 14:25:30 -0000 Received: from unknown (HELO optusnet.com.au) (unknown) by unknown with SMTP; 31 Aug 2002 14:25:30 -0000 Message-ID: <3D70D1FC.1040306@optusnet.com.au> Date: Sun, 01 Sep 2002 00:26:04 +1000 From: Antony Mawer User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.1b) Gecko/20020819 X-Accept-Language: en-au, en-us, en, ja MIME-Version: 1.0 To: freebsd-stable@FreeBSD.ORG Subject: Re: write cache not actually disabled by sysctl? References: <3D6CBC64.7050205@optusnet.com.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I neglected to mention, this is on FreeBSD 4.6 -STABLE as of August 10th. -Antony Antony Mawer wrote: > After reading about the potential dangers assocaited with enabling the > write cache on ATA drives in combination with softupdates, I've recently > added the following to /boot/loader.conf: > > hw.ata.wc="0" > > Once booted, running sysctl confirms that this is set: > > [root@gibson] ~# sysctl hw.ata.wc > hw.ata.wc: 0 > > However, looking at the atacontrol cap output, it appears that write > caching is still enabled on both ATA drives (see below). Can I trust the > information from atacontrol cap to be accurate? And if so, why is write > caching enabled when the sysctl is explicitly set to off? The system was > rebooted after adding the change to loader.conf to allow it to take > effect... > > I'm not overly worried by sacrificing some performance for potentially > increased safety gains as disabling write caching involves... > > Any thoughts? > -Antony > > [atacontrol output below] > > > > [root@gibson] ~# atacontrol cap 2 0 > ATA channel 2, Master, device ad4: > > ATA/ATAPI revision 5 > device model ExcelStor Technology CT210 > firmware revision ES4CA53D > cylinders 16383 > heads 16 > sectors/track 63 > lba supported 20040450 sectors > lba48 not supported > dma supported > overlap not supported > > Feature Support Enable Value Vendor > write cache yes yes > read ahead yes yes > dma queued no no 0/00 > SMART yes no > microcode download yes yes > security yes no > power management yes yes > advanced power management no no 0/00 > automatic acoustic management no no 0/00 0/00 > > > [root@gibson] ~# atacontrol cap 3 0 > ATA channel 3, Master, device ad6: > > ATA/ATAPI revision 5 > device model QUANTUM FIREBALLlct20 10 > firmware revision APL.0900 > cylinders 16383 > heads 16 > sectors/track 63 > lba supported 20044080 sectors > lba48 not supported > dma supported > overlap not supported > > Feature Support Enable Value Vendor > write cache yes yes > read ahead yes yes > dma queued no no 0/00 > SMART yes no > microcode download yes yes > security yes no > power management yes yes > advanced power management no no 0/00 > automatic acoustic management yes no 0/00 0/00 > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message