Re: CDROM jukebox filesystem using autofs
H. Peter Anvin (hpa@transmeta.com)
30 Apr 1998 22:14:59 GMT
Followup to: <slrn6khg06.8pc.aaronp@ofb.net>
By author: aaronp@ofb.net (Aaron Passey)
In newsgroup: linux.dev.kernel
>
> On Thu, 30 Apr 1998 10:10:57 -0500, Dan A. Dickey <ddickey@wamnet.com> wrote:
> >Aaron Passey wrote:
> >> There are several problems I am running into with this approach.
> >> First of all, what do I do if I have 4 drives, all mounted and busy, and I
> >> get a request for a fifth disk?
> >
> >return EBUSY.
>
> Are you suggesting that when disks 1-4 are mounted and busy
> and I do an ls on /autofs/5, the ls gets an EBUSY? This doesn't
> make much sense. Normal small CDROM jukeboxes I have seen working
> under Linux allow you to have all of the disks mounted and they swap
> disks as necessary. These are done by multiplexing at the block
> device level so you get a /dev/scd0 - /dev/scd5 for a 6 disk
> changer. The jukebox I am writing a driver for has hundreds of
> disks so it seems impractical to do this -- hence my autofs
> approach. Using the autofs model, the only choices I have are to
> grant a request from the kernel or say it doesn't exist (the process
> gets a File not Found and a negative dentry is created). I can
> modify autofs to also support sending an EBUSY but is this desired?
I think the way to do this is going to involve some amount of disk
caching if you want it to work sanely.
-hpa
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