Date: Sat, 17 Apr 2004 13:30:50 +0000 From: Andy Smith <andy@strugglers.net> To: freebsd-stable@freebsd.org Subject: mfs and vnconfig questions out of curiosity Message-ID: <20040417133050.GL79111@cashmere.blitzed.org>
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--5p8PegU4iirBW1oA Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi there, I haven't yet had any cause to use memory filesystems in FreeBSD, but I was just reading about them the other day and I came across references to malloc-backed and swap-backed. I have read the man page for vnconfig and mfs on -STABLE, and for mdconfig on -CURRENT, but I'm still a little confused and would appreciate some clarifications. So I have a few questions which I will try to keep relevant to -STABLE, although if the situation has significantly changed in -CURRENT then a commnent about that would be appreciated too.. So you can make a swap-backed filesystem in -STABLE with vnconfig -S, but why would you ever want to do this? Why is this preferred over just using a regular file? Then there is malloc-backed filesystem as created with mfs in STABLE. Presumably this works with virtual memory and lazy allocation the same way as malloc() from a program would do, i.e. it is possible to create an FS that is bigger than the amount of physical memory in the system, and whenever files are stored in the FS it is similar to any other request to the VM system, may be satisfied with real memory or go into swap? I understand that in -CURRENT, mdconfig replaces vnconfig for managing MFS that are either malloc-backed, swap-backed or file-backed, right? --=20 Encrypted mail welcome - keyid 0xBF15490B > > > The optimum programming team size is 1. Has Jurassic Park taught us nothing? -- pfilandr@mindspring.com, news:comp.lang.c --5p8PegU4iirBW1oA Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAgTGKIJm2TL8VSQsRAqYzAJ0SnUeYYPvhPk8Jn2sxB5+Z5I4+fACeJqBy sYwNhmFo0sGgZEdQuXM2UVA= =UvNq -----END PGP SIGNATURE----- --5p8PegU4iirBW1oA--
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