Re: udev & kernel names

[Nishanth Aravamudan <nacc@us.ibm.com>]

* Greg KH <greg@kroah.com> [2005-0427 09:05:46 -0700]:

> On Tue, Apr 26, 2005 at 04:15:16PM -0700, Nishanth Aravamudan wrote:
> > Greg, udev Developers,
> > 
> > One of the most valuable features of new udev-based system is persistent
> > device naming. This is especially useful for large systems, which may
> > involve upwards of 4000 disks. Rather than determining which disk is
> > sdzz, the administrator can name it tray15_disk7 and thus easily access
> > the drive. We all know this much, though.
> > 
> > Another interesting idea would be to somehow inform the kernel of these
> > new names (sysfs?).
> 
> Um, didn't we talk about this before?
> 
> And didn't I get across the point that this is pointless, wrong, and
> will never happen? :)

Sorry, Greg, I wasn't part of that conversation. Thanks for the
information that this won't happen.

> > The gist being that currently, even though udev has
> > created a new dev node for the device, the kernel is unaware of this
> > ``name'' when reporting errors. I think it could be very useful for our
> > friendly sysadmin to see ``tray15_disk7 has failed'' rather than ``sdzz
> > has failed.'' Or perhaps they want to offline an entire tray; it would
> > be simpler in scripts to refer to ``tray15_*'' than the appropriate
> > kernel device nodes.
> > 
> > My questions are:
> > 
> > Is this feasible?
> 
> No.
> 
> > Would a new file per-device in sysfs be the appropriate place for this?
> 
> No.
> 
> > Is there a better way to go about getting these useful log messages?
> 
> Modify your syslog program to do it.

Would it make some sense then to make an udev-aware syslog program? If
such a package were created, would it be possible to integrate it with
the udev package? Or, minimally, provide some documentation as to how to
make the modifications oneself?

> Oh, and what about the fact that I can create 2 device nodes in the fs
> that really are the same kernel device?

I never said my proposal was perfect :) I was trying to find out what
was possible and what wasn't. You answered that fine.

> /me watches the ras developers get all agitated
> 
> > If I need to clarify the problem/proposed solution further, please let
> > me know.
> 
> Please let me know who is trying to drive such a misguided and
> ill-conceived issue and I will track them down...

I will see if I can get you some names :)

Thanks,
Nish


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