Date: Sat, 3 Mar 2007 11:09:40 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Alan Amesbury <amesbury@umn.edu> Cc: freebsd-performance@freebsd.org Subject: Re: (S)ATA performance in FBSD 6.2/7.0 Message-ID: <20070303110940.32893388@Magellan.Leidinger.net> In-Reply-To: <45E8B994.2010100@umn.edu> References: <20070302120018.5830716A4A9@hub.freebsd.org> <45E8B994.2010100@umn.edu>
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Quoting Alan Amesbury <amesbury@umn.edu> (Fri, 02 Mar 2007 17:56:04 -0600): > Looking at /usr/include/sys/mount.h, I see that there are two flags > defined: MNT_SYNCHRONOUS and MNT_ASYNC. I'm not sure why both flags > exist, but suspect the former was added so you could mount UFS/FFS/UFS2 > filesystems that had soft updates enabled in synchronous mode without > having to umount the filesystem, use tunefs(8)'s "-n" flag to > enable/disable soft updates, then remount the filesystem with the > appropriate flag(s). In FreeBSD we have 3 types, not 2. We have "sync", "noasync" (default) and "async". With noasync the meta-data is written in sync mode and the data is written in async mode. For async the complete IO is done asynchronous (the meta-data too). And for sync the complete IO is synchronous. mount(8) tells this with some more words. Bye, Alexander. -- As a math atheist, I should be excused from this. -- Calvin http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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