Re: udev and devfs - The final word

viro
2004-01-05T03:50:46Z

On Sun, Jan 04, 2004 at 07:33:16PM -0800, Linus Torvalds wrote:
> Ahh. I'll buy into that, and yes, this is an example of something that
> needs to be fixed.
>
> It shouldn't be fixed by saying "device numbers have to be stable across
> reboots", because the fact is, we're most likely going to have storage
> that is really really hard to enumerate in a repeatable fashion.
>
> So the _proper_ thing to do is to have the NFS server not use the device
> number as part of fsid. It should use the _stable_ UUID of the filesystem
> or some similar label.

... and we already have a way to specify it explicitly. Which, BTW, allows
to take server down, copy exported fs from failing IDE disk to SCSI one and
reexport. With clients remaining happy with you. Remember discussions
circa 2.5.50 or so about that stuff?

So we have tools for that. And it's 100% OK to say "if you are doing NFS
export of filesystem that lives on $new_weird_device, explicit fsid= is
not just a good idea, it's a must-have".

What is _not_ OK, though, is to have folks suddenly see /dev/hda3 changing
its device number - then we would break existing setups that worked all
along; even if admin can fix the breakage, it's not a good thing to do.