RE: scsi disk detection and /dev names, RE: My $.02 on the ragin

Shawn Leas (SLEAS@videoupdate.com)
Mon, 11 Oct 1999 16:18:34 -0500


From: hpa@transmeta.com [mailto:hpa@transmeta.com]
Subject: Re: scsi disk detection and /dev names, RE: My $.02 on the raging
de vfs debate

I appreciate the commentary you have brought to this debate,
as it was, until now, re-hashing tired old points.

>A few more things to remember when you're talking about
>"location-based names":

>1. PCI bus numbers are fairly volatile; they are assigned sequentially
> by a depth-first search. Inserting a multiport Ethernet card
> (which usually have PCI-PCI bridges onboard) could move a whole lot
> of bus numbers for you. Same thing with SCSI controller numbers.

I only happens when you plug/un-plug PCI devices, including
host adapters. What if you turn on your PC with the one or
two external SCSI hard drives removed, and you were using
the disk or partitions raw, as with LVM? Methinks you're
screwed.

>2. Consider if location-basis is really what you want, and if so, if
> it really matters. Rearranging your SCSI busses, for example, is
> probably quite common. On busses where you have device serial
> numbers, or for disks where you have labels, it probably would
> provide a better basis.

Not with the above, most relevant example.

>3. Solaris seems to teach the lesson that if you make the device names
> too complex, noone will use them. Solaris has a very complete
> location-based device naming scheme, but I know very few Solaris
> administrators who use those names, as opposed to the short
> symlinks.

That's why devfs is SO COOL!!! You still have /dev/sda, and automatically
I might add, but you also have location based naming to use if needed.

It only adds flexibility, nothing else. What if Solaris had an option
where you could turn the location naming off altogether?? I'd say
some admins would be astounded by the flexibility of the cool OS!
And BTW, I thought the whole naming scheme was a SYSV thing, not a
Solaris one...

-Shawn

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