I have an issue regarding scsi device node assignment to scsi device in
Linux.
As current device node assignment, Linux will assign a detected scsi device
with next available device node, namely sdb, sdc, sdd, ... etc. The device
node itself dosn't have information about card number, taget id or LUN
compare with the dvice node in Unixware or Solaris which has those
information available in device node.
It works OK until I am trying to do persistent binding for our fibre channel
HBA.
Considering if a system has one scsi driver as primary boot device, and a
fibre channel HBA which connected with JBOD, RAID and other FC devices on
fabric, or even simplier, just hooked with a JBOD. Persistent binding
requires device node (or device - mount point pair) to be consistent from
boot to boot. Currently what we can do is to assure that from boot to boot
that the devices connected with our FC HBA are persistent even user swaped
devices, or added new devices in FC loop or fabric. The problem comes when
there is a new scsi device added in the system (or another HBA added in
which take place in front of our HBA). Then at very next reboot, those new
added scsi device will be scanned first and be assigned with those available
device node which could be used by our HBA at last boot. This will ruine
the persistent binding. (e.g. from last boot, we have sda assigne to primary
scsi device, sdb, sdc, sdd assigned to FC devices. Now the new added scsi
device will take sdb. The device node assigned to fc device became sdc, sdd
and sde).
If Linux scsi device node assignment is nased on slot, or has card, target
and lun information associated with, then even new scsi devices are added in
the front, we can still keep our previous assigned device node for
persistent binding.
Is there a way for driver to force Linux to reserve the device node that has
been assigned to a particular device?
If not, any suggestion to resolve the issue?
By the way, this is not a problem for other UNix such as Solaris, both Sparc
and x86 where our persisten binding works just fine.
Many thanks!
Eddie Wang
Agilent Technologies
350-370 West Trimble Road
MS 90TZ
San Jose, Ca 95131-1008
Phone: (408) 435-4213
Fax: (408) 435-5838
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