Date: Tue, 19 Jun 2001 20:04:07 -0700 From: Dima Dorfman <dima@unixfreak.org> To: Mikhail Teterin <mi@aldan.algebra.com> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sbin/mdmfs Makefile mdmfs.8 mdmfs.c pathnames.h Message-ID: <20010620030407.C8A433E2F@bazooka.unixfreak.org> In-Reply-To: <200106200256.f5K2uO628234@aldan.algebra.com>; from mi@aldan.algebra.com on "Tue, 19 Jun 2001 22:56:23 -0400 (EDT)"
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Mikhail Teterin <mi@aldan.algebra.com> writes: > On 19 Jun, Dima Dorfman wrote: > > Mikhail Teterin <mi@aldan.algebra.com> writes: > >> On 18 Jun, Dima Dorfman wrote: > >> > dd 2001/06/18 16:46:58 PDT > >> > > >> > Added files: > >> > sbin/mdmfs Makefile mdmfs.8 mdmfs.c pathnames.h > >> > Log: > >> > Introduce mdmfs(8), a wrapper around mdconfig(8), disklabel(8), > >> > newfs(8), and mount(8) that mimics the command line option set of the > >> > deprecated mount_mfs(8). > >> > > >> > Approved by: jkh, phk, -hackers > >> > >> So, will > >> > >> /dev/da0b /tmp mfs rw,async > >> > >> Just Work (TM) now? > > > > Besides the fact that mdmfs(8) isn't installed as /sbin/mount_mfs, > > there are two things wrong (from mdmfs's point of view) with that > > line: > > > > * /dev/da0b -- this should either be "/dev/md" for autounit, > > or "/dev/mdX" where X is the desired unit number. This small > > incompatibility is intentional: I don't think it's a good idea for > > users to blindly assume that md(4) is mfs; at least if they have to > > change that, they'll know that something might be different. > > Ok... For being entirely compatibile, mdmfs should check if the > specified partition is being used for paging. If it is, md should use > the /dev/md and use swap as backing for the memory disk. If it is not, > it should use /dev/md and the specified disk as vnode-backing. See above. I don't want people to just symlink mdmfs to mount_mfs and off they go; that can lead to foot shooting if they make assumptions about mfs that don't work for md. I don't think it's too much to ask to change /dev/da0b to /dev/md. > > * There's no size specification. The only way I've seen MFS used is > > with an -s argument in the options field; e.g., "rw,async,-s<size>". > > If your example works without -s (i.e., mount_mfs assumes a default > > size), mdmfs should be fixed to do that too; although I don't know > > what the default size should be. > > Well, with the mfs the default is the size of the partition (da0b). I suppose it might be possible to use, say, half the swap size of the system. I think what mfs allegedly did is quite silly; who wants to use their *entire* swap space for a filesystem? Better yet, people can explicitly set the size; I wouldn't think of doing it otherwise. > > > If you find any [other] differences in behavior in mdmfs vs. the old > > mount_mfs, please let me know. I used the mount_mfs(8) man page as the > > reference, not the code, so there may well be some. > > For those, who modified the /etc/fstab, it should be possible to specify > the type of md as a mount option explicitly. What do you mean "type of md"? As in malloc- or swap-backed? You can do that. This: /dev/md /tmp mfs -M,rw,async will set up malloc(9) backing; this: /dev/md /tmp mfs -F/usr/myfile,rw,async will set up vnode backing on /usr/myfile. Swap backing is the default. See the man page for details. Dima Dorfman dima@unixfreak.org > > How is that? > > -mi > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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