Does anyone know how to configure a linux kernel to detect sparse luns in RedHat 9.0? I have a SCSI device that 4 luns(0,1,3,16) and RedHat is only detecting the first 2. Additionally, The Qlogic driver that was shipped in the RH9 distribution is not allowing 16-byte CDB's. I have checked the SCSI Generic source code and found a #define for the maximum CDB size to be 16. Where else should I look to find the restriction?

Thanks,
Nate

I found the answer I needed to fix the sparse lun issue.

1. cat /proc/scsi/scsi

find the device that has the sparse luns and get the vendor and model data.

2. edit /usr/src/linux-2.4/drivers/scsi/scsi_scan.c so that
static struct dev_info device_list[] has the following entry in it.

{"vendor", "model", "*", BLIST_SPARSELUN | BLIST_LARGELUN},

3. rebuild module/kernel


Real example follows:

My /proc/scsi/scsi showed this, which only shows LUN 0 and 1 --- it is missing 3 and 16.
> Host: scsi0 Channel: 00 Id: 00 Lun: 00
> Vendor: Pillar Model: Axiom 500 Rev: 0000
> Type: Direct-Access ANSI SCSI revision: 05
> Host: scsi0 Channel: 00 Id: 00 Lun: 01
> Vendor: Pillar Model: Axiom 500 Rev: 0000
> Type: Direct-Access ANSI SCSI revision: 05


Line I added to static struct dev_info device_list[] in /usr/src/linux-2.4/drivers/scsi/scsi_scan.c


{"Pillar", "Axiom 500", "*", BLIST_SPARSELUN | BLIST_LARGELUN},

I added this line right before the last entry which is {NULL, NULL, NULL}

I now see all 4 LUNs. Special thanks to Michael Clark.

Nate

One other note. For SCSI in lk 2.4, the maximum default cdb size is 12. This value can be overridden in the individual driver or can be changed in usr/src/linux-2.4/drivers/scsi/hosts.c by replacing retval->max_cmd_len = 12; with retval->max_cmd_len = 16;.
If you have legacy SCSI devices that don't support 16 byte cdb's you should override the value in the individual driver and leave the default as 12 in host.c.

Nate

For what it's worth ... LINUX 2.6.5 kernel with the same qlogic drivers support 16-byte CDBs. I tested on both 32-bit and ia64-bit distributions. Other kernels may work, but even after trying some patches to 2.4 kernels, I never got it to work.

Note also that you have to make sure your driver supports 16-byte CDBs.