Date: Thu, 26 May 2005 12:53:02 -0500 From: Eric Anderson <anderson@centtech.com> To: Bjoern Koenig <bkoenig@cs.tu-berlin.de> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Disable read/write caching to disk? Message-ID: <42960CFE.4060307@centtech.com> In-Reply-To: <42960ACB.7090801@cs.tu-berlin.de> References: <4295D51F.50106@centtech.com> <429606D9.6080602@cs.tu-berlin.de> <42960ACB.7090801@cs.tu-berlin.de>
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Bjoern Koenig wrote: > Bjoern Koenig wrote: > >> Eric Anderson wrote: >> >>> Is it possible to disable all read and write caching to a disk? >> >> >> You can disable write the cache by adding the line >> >> hw.ata.wc="0" > > > I assumed that you use ATA. If you use SCSI devices then read at least > the manpages da(4) and camcontrol(8). Thanks.. I've just read (quickly) both man pages. It seems as though you are suggesting disabling the physical disk caching, which should not make a difference in my case. The disk would report whatever it needs to report to either host, and those should be in sync. When I mount the filesystem on host B ro, it shows me the filesystem as of the time that I mounted it ro. Any subsequent changes on host A (which has it mounted rw) are not seem on host B unless I unmount and mount again on host B. This seems like a FreeBSD feature and not a general scsi feature. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology A lost ounce of gold may be found, a lost moment of time never. ------------------------------------------------------------------------
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