Zitiere Jamie Lokier <lk@tantalophile.demon.co.uk>:
>
> As it happens, even with your multi-volume scheme
> I will get that behaviour because the editor
> always writes to /floppy anyway.
Yes, the multi-volume scheme is doesn´t allow you to
work with multiple volumes at the same time, it only
allows a better recovery than revoke if the user
accidentially removed a disk.
>
> If it's a database it can keep open a directory
> handle on that disk.
> When the disk is removed, the handle is revoke()d as
> are any open files, and further operations by the
> database program fail.
Exactly. -EPLEASEREENTERYOURCHANGES.
I want to avoid that.
That´s the only advantage of the multi-volume scheme.
> (It's possible to
> hook these failures in user space if you want to
> implement a volume daemon).
>
I´ll think about it, but the daemon needs a way to
recover from these failues.
> It's unclear whether GUIs would see the multiple
> volumes or not.
It shouldn´t see them.
Just to clarify, unless you keep a database open on a
floppy
* usually 1 disk is mounted.
* 2 disks are mounted during media change. The second
disk is unmounted as soon as the OS notices that no
open file handles are left. Usually before the syscall
which noticed the media change returns.
If open handles exist, then the second superblock is
not destroyed, and allows recovery if the database
wants to write to the open handle.
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This archive was generated by hypermail 2b29 : Fri Jun 23 2000 - 21:00:25 EST