Date: Fri, 05 Nov 1999 01:26:31 -0800 From: "Ronald F. Guilmette" <rfg@monkeys.com> To: freebsd-questions@freebsd.org Subject: Questions about memory filesystems. Message-ID: <16804.941793991@monkeys.com>
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Some questions: Is there any such thing as a tutorial anywhere on the proper setup and use of a memory filesystem? Or does the mount_mfs man page really tell me all I need to know? If I want to create a memory filesystem of, of, say, 64MB, do I really need to first allocate a 64MB disk partition on my disk drives somewhere and then provide the /dev/ name of that to the mount_mfs command as the ``special'' device file parameter? The man page for mount_mfs says that when you unmount one of these memory files systems, all data in that (former) filesystem is lost. OK... Simple question: Why? I note that the same man page also says that ``The special file is typically that of the primary swap area, since that is where the file system will be backed up when free memory gets low and the memory supporting the file system has to be paged.'' OK, so if the system is smart enough to page out some parts of one of these memory filesystems when it gets generally low on memory, then why shouldn't it also be smart enough to simply (a) page out the *whole* filesystem to some designated hunk of disk space as/when the memory filesystem is being unmounted, and then (b) page the whole thing back in again (presumably from the same hunk of disk space) when the thing gets mounted again? That would provide a nice sort of persistance effect for these memory filesystems, even across (orderly) reboots. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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