Date: Tue, 19 Jun 2001 23:25:14 -0400 (EDT) From: Mikhail Teterin <mi@aldan.algebra.com> To: dima@unixfreak.org 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: <200106200325.f5K3PF628641@aldan.algebra.com> In-Reply-To: <20010620030407.C8A433E2F@bazooka.unixfreak.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 19 Jun, Dima Dorfman wrote: >> >> 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. I don't know... There is a lot of value in being backwards compatible... May be with a big warning, but after an upgrade, the system should just keep on working. IMHO, that is. >> > * 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? The filesystems used swap space dynamicly, AFAIK. As in Solaris -- your files in /tmp and your swap use grew to meet each other in the middle somewhere. That way, you did not have to guess, how much to allocate for FS and how much to leave availalble. >> 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 Yes, that's what I meant. Cool. -mi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200106200325.f5K3PF628641>