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SubjectRe: Ideas for v2.1
>>>>> "Werner" == Werner Fink <werner@suse.de> writes:

>> Date: 13 Jun 1996 12:28:20 +0200 From: barnard@forge.franken.de
>> (Henning Schmiedehausen)
>>
>> duprec@jsp.umontreal.ca (DUPRE Christophe) writes:
>>
>> >Not really a good idea : Let's say you have IDE and SCSI
>> disks: >/dev/hda, /dev/hdb, /dev/sda and /dev/sdb
>>
>> >With your system, you'd have: >/dev/hda -> /dev/diska
>> >/dev/hdb -> /dev/diskb >/dev/sda -> /dev/diskc >/dev/sdb ->
>> /dev/diskd
>>
>> >Now one IDE disk is crashed and you remove it. Thus /dev/hdb
>> no longer >exists, and you get this mapping: >/dev/hda ->
>> /dev/diska >/dev/sda -> /dev/diskb >/dev/sdc -> /dev/diskc
>>
>> So, lets see, how it is currently:
>>
>> I have
>>
>> /dev/hda -> IDE /dev/sda -> SCSI ID0 /dev/sdb -> SCSI ID3
>> /dev/sdc -> SCSI ID4 /dev/sdd -> SCSI ID5
>>
>> Now I remove SCSI ID3. 'drive does not spin underwater error'
>>
>> /dev/sda -> SCSI ID0 /dev/sdb -> SCSI ID4 /dev/sdc -> SCSI ID5
>>
>> :-(
>>
>> Not too different from the scheme you criticized above. But it
>> is already in there. And IMHO it sucks. :-(
>>
>> Ciao Henning
>>
>>

Werner> Why not mapping ID<num> on /dev/sd<alph>

Werner> /dev/sda <-> SCSI-Disk ID0 /dev/sdb <-> SCSI-Disk ID1
Werner> /dev/sdc <-> SCSI-Disk ID2

Werner> No SCSI-Disk with ID1 means no /dev/sdb ... and so on

This assumes you have only one SCSI controller.

How about sd1a1 being the first controller (1-n controllers), the
first disk (a-z disks), and the first partition (1-n partitions)? By
using a letter in the middle, you can have a device like sd12d11
without becoming confused as to which digits signify which IDs.

Of course we could adopt something like sdc0d2p1, which is more like
Solaris, and others. We may even want to create a /devices directory,
and put all the hardcoded nodes in there with complex ID oriented
names and directory heirarchies, and then have /dev be standard-named
symlinks to those devices. The software people get to use the names
they want, and the hardware people stand a chance of identifiying
which piece of hardware they are troubleshooting.

The thing we have to avoid is having drives switch /dev names, since
it is those names which are used in files like /etc/fstab. How can we
mount a series of filesystems if we don't know which disks we will
actually get?

---
Andrew C. Esh mailto:andrew_esh@cnt.com
Computer Network Technology andrewes@mtn.org (finger for PGP key)
6500 Wedgwood Road 612.550.8000 (main)
Maple Grove MN 55311 612.550.8229 (direct)
http://www.cnt.com - CNT Inc. Home Page
http://www.mtn.org/~andrewes - ACE Home Page


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