Re: vsta mount tutorial

[brtmac@ksu.ksu.edu writes:]

>First, I was under the impression that it was possible to mount a
>filesystem on top of a directory and still be able to see the existing
>directory (stackable or translucent filesystems). I haven't been able
>to figure out how to do this.

Yes, although this code has been exercised little.

>Second, I've created a large file in the / directory on a dos
>filesystem with the mkfs_vfs program, and then run a vstafs server
>using it as the datastore. This works fine and I can mount it and
>use it (way cool!). I mounted it as /v and copied /vsta to /v.
>Then I tried mounting the vstafs filesystem on /vsta. That worked.
>So then I removed everything from the /vsta directory on the dos
>partition that wasn't needed for booting, and changed the inittab
>and fstab files to automatically start the vstafs and mount it on
>/vsta.

Ballsy. I just started playing with vstafs again after a LONG time. I have
some pretty good optimizations for I/O, but also hope to shake out some of
the remaining problems. You used the "-p" flag when you made the
filesystem, right?

>After rebooting, things seemed okay, except that some things quit
>working properly. ps started giving weird results in the USR/SYS
>column, and vi and less started complaining about the terminal type
>not being found. Basically, it appered that for certain operations,
>the /vsta directory on the dos filesystem was being searched, and not
>the /vsta filesystem being served by the vstafs server.

ps giving weird results is puzzling--you're going to have to do some debug
on *that* one. It sounds like this filesystem was not mounted when you
thought it was. Without seeing the actual boot.lst, inittab, and fstab
files I can't say for sure.

>Any help in clearing up my understanding of this would be greatly
>appreciated.

vstafs is little used, and has definitely not been tried out as the /vsta
fileserver when running from a DOS file. There are certainly going to be
problems with I/O flushing, as so far as DOS can tell the vstafs server is
just holding some file open indefinitely--so he won't be doing I/O on it
the way vstafs thinks his "disk" would.

A fun configuration to get going, but be prepared to do some debugging along
the way. Also, vstafs is a lightly used server so far as I can tell. I
just got a dedicated partition for it onto my central development machine,
so expect more activity on it in the near future.

                                                        Andy
Received on Mon Nov 28 15:35:24 1994