From owner-freebsd-questions Tue Dec 15 10:01:25 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA28377 for freebsd-questions-outgoing; Tue, 15 Dec 1998 10:01:25 -0800 (PST) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from pau-amma.whistle.com (s205m64.whistle.com [207.76.205.64]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id KAA28372 for ; Tue, 15 Dec 1998 10:01:22 -0800 (PST) (envelope-from dhw@whistle.com) Received: (from dhw@localhost) by pau-amma.whistle.com (8.9.1/8.9.1) id KAA08793; Tue, 15 Dec 1998 10:00:04 -0800 (PST) (envelope-from dhw) Date: Tue, 15 Dec 1998 10:00:04 -0800 (PST) From: David Wolfskill Message-Id: <199812151800.KAA08793@pau-amma.whistle.com> To: freebsd-questions@FreeBSD.ORG, pavel@ikar.elect.ru Subject: Re: What does it mean MFS ? In-Reply-To: Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >Date: Tue, 15 Dec 1998 16:02:15 +0300 (MSK) >From: "Pavel V. Antipov" >Subject: What does it mean MFS ? "MFS" is "Memory File System" -- a file system that resides in memory. As such, it does not persist across a reboot (though it may, and often is, re-created at reboot, when /etc/rc is running). For sets of files that are sufficiently small (which is going to be dependent on your circumstances), reading and writing files to an MFS need not involve disk I/O at all. Thus, use of an MFS can be a win, if the data in question do not need to be retained across a reboot. I tend to mount /tmp on an MFS, for example; this also obviates the need to clear /tmp on reboot. There are (superficial?) resemblances netween the FreeBSD MFS and the SunOS TMPFS, if that helps. Also, I understand that Kirk McKusick's "soft updates" can reduce the incentive to make use of MFS, since with soft updates, a short-lived file may never be written to disk. (Again, the noted effect is that I/O to and from the file would be written to disk only if necessary, thus minimizing the time-consuming disk I/O; avoiding slow things is often helpful for performance.) david -- David Wolfskill UNIX System Administrator dhw@whistle.com voice: (650) 577-7158 pager: (650) 371-4621 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message