adding callouts to udev for scsi identifiers/serial numbers

[Patrick Mansfield <patmans@us.ibm.com>]

Hi -

I have a scsi_id program intended for use with udev to retrieve SCSI
serial number/id's using INQUIRY page 0x80 or page 0x83. scsi_id dumps a
unique ID to stdout and exit's with zero status; if no id, it exit's with
non-zero status.

I'm working on extending udev to invoke and use the value retrieved via
scsi_id.

For small configurations, adding syntax such as the following to a
namdev.config works OK:

CALLOUT, PROGRAM="/usr/sbin/scsi_id", BUS="scsi", ID="200609487340b71da", NAME="disk-1"

I have a udev patch for the above (and can post it if anyone wants to see
it).

For larger configurations, with many disks in a namdev.config file (my
test system has about 50 entries) each configuration line calls out to get
the id, and things slow down quite a bit.

For example, running (via command line) udev + scsi_id for 48 /sys/block
entries with a corresponding number of callout entries in namedev.config
takes about 15 seconds; a simple (not fully functional) caching of the
scsi_id results gets this down to about 1.3 seconds.

In order to call out and cache one time, I was thinking of adding
namedev.config syntax like:

SET=somevar1, BUS="scsi", PROGRAM="/usr/sbin/scsi_id"

USE=somevar1, BUS="scsi", ID="200609487340b71da", NAME="disk-1"
USE=somevar1, BUS="scsi", ID="somenumber", NAME="disk-2"

Any comments or suggestions on the above?

Thanks.

-- Patrick Mansfield


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