Date: Tue, 15 Dec 1998 10:00:04 -0800 (PST) From: David Wolfskill <dhw@whistle.com> To: freebsd-questions@FreeBSD.ORG, pavel@ikar.elect.ru Subject: Re: What does it mean MFS ? Message-ID: <199812151800.KAA08793@pau-amma.whistle.com> In-Reply-To: <Pine.BSF.3.96.981215160156.7815A-100000@ikar.elect.ru>
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>Date: Tue, 15 Dec 1998 16:02:15 +0300 (MSK) >From: "Pavel V. Antipov" <pavel@ikar.elect.ru> >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
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