Poor device management

John Goerzen (jgoerzen@complete.org)
19 May 1998 00:08:26 -0500


I would like to address the topic of naming of devices. Currently, we
have two serious problems:

1. It appears that Linux can support a maximum of 16 SCSI hard drives
per system, according to devices.txt.

This is a serious issue as we would like to have more than that on
some machines but the OS does not appear to support that. The
allocated block of device numbers appears to have no support for more.

2. Device numbers can change between boots or even during operation.

This is because the device numbers (and thus, /dev entries) are
allocated in sequential order. Thus, for instance, if my Jaz drive
(SCSI ID 4) is turned off but my scanner (ID 5) is on, the scanner
gets a particular device assigned to it. However, it the Jaz drive is
on when the system boots, the Jaz gets that ID and the scanner gets
something different.

It would, therefore, be highly advisable to go to something akin to
Solaris -- the /dev entries specify controller, target, and LUN
expliticly. This will remove a lot of confusion especially
surrounding the sg devices and eliminate the problem of drifting
device entries.


John Goerzen        Linux, Unix programming           jgoerzen@complete.org |
Developer, Debian GNU/Linux (Free powerful OS upgrade)       www.debian.org |
``You'll notice that this scanner, Bill [Gates]...''  <Blue Screen of Death>
``Whoa!''  <Applause>   ``Moving right along....''  -- Microsoft (Comdex
      video at: http://cnn.com/TECH/computing/9804/20/gates.comdex/index.html

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