Re: devfs patch v3

ralf@uni-koblenz.de
Mon, 12 Jan 1998 11:20:29 +0100


On Mon, Jan 12, 1998 at 07:36:03AM +1100, Richard Gooch wrote:

> Pavel Machek writes:
> > Hi!
> >
> > > > where <H> is the host controller number, <C> is the channel number,
> > > > <I> is the SCSI disc ID, <L> is the LUN.
> > > > For a single partition it looks like this:
> > > >
> > > > sd_hHcCiIlLpP
> > > >
> > > > where <P> is the partition number. So, for example sd_h0c0i3l0p2
> > > > corresponds to sdd2 on my system.
> > >
> > > Wouldn't it be better to use subdirectories as much as possible?
> > > I know it will be more difficult to implement, but will make things look
> > > nicer, readdir faster, etc.
> > > What about
> > > /dev/sd/hHcCiIlL
> > > /dev/sd/hHcCiIlLpP
> > > /dev/pts/N
> > > /dev/scd/hHcCiIlL /* current cdrom code doesn't use partitions */
> > > ...
> >
> > In case of devfs, only those who are actually installed take up space
> > in /dev. Is that still problem? (I would not like to have /dev
> > multi-directory, because it would make manual looking for devices
> > harder (by one or more chdirs).) Hmmmm. Thinking about sunsite. That
> > is I believe something like 50 scsi discs, and you probably have about
> > 2 devices per disc (h...lL and h...lLpP), that's about 100 entries,
> > which is perfectly ok. I think that even 1000 discs would be ok
> > (altrough not good), since entries are in RAM and readdirs are not
> > done too much, anyway.
>
> You're assuming for large disc farms there are few partitions per
> disc. That might not be true (maybe each user gets their own striped
> partition).

Sybase wants disks partitioned in 2gb chunks when using raw devices. I've
got a box with 48 disks, that sucks ... There are 43gb disks available and
Solaris is limited to 7 useable partitions, so we also shouldn't limit
ourselves unless we have to ...

Ralf