Compiling a new RHEL-4 kernel

[Simon]

On Dec 21, 2005, at 4:33 AM, Nigel Wade wrote:
>
>
> You ought to have a different sg device for each LUN if sg is  
> working correctly. At least that's what I get for multiple LUNs on  
> a SCSI RAID. Each LUN on the RAID has a different sg device, and is  
> mapped to a different sd device.
>
> What is the contents of /proc/scsi/sg/devices? This should show you  
> the SCSI id and LUNs of all identified SCSI devices on the system.

Well, it doesn't mean much to me, but here it is:

[root at www4 ~]$ cat /proc/scsi/sg/devices
1       0       0       0       0       1       4       0       1
1       0       1       0       0       1       4       0       1
1       0       8       0       3       1       2       0       1
2       0       0       0       0       1       63      0       1
2       0       15      0       3       1       3       0       1
2       1       5       0       1       1       3       0       1
2       2       15      0       3       1       3       0       1

>
> Do you have sg3_utils installed? If not I'd suggest doing so, this  
> package really helps with sorting out sg/st/sd assignments. For  
> example, sg_scan on my system show this:

Yep:

[root at www4 ~]$ sg_scan -i
/dev/sg0: scsi1 channel=0 id=0 lun=0
     IBM-ESXS  MAP3735NC     FN  C101 [rmb=0 cmdq=1 pqual=0 pdev=0x0]
/dev/sg1: scsi1 channel=0 id=1 lun=0
     IBM-ESXS  VPR073C3-ETS10FN  S370 [rmb=0 cmdq=1 pqual=0 pdev=0x0]
/dev/sg2: scsi1 channel=0 id=8 lun=0
     IBM       39M6750a S320  0  1    [rmb=0 cmdq=0 pqual=0 pdev=0x3]
/dev/sg3: scsi2 channel=0 id=0 lun=0
     IBM       SERVERAID         1.00 [rmb=0 cmdq=1 pqual=0 pdev=0x0]
/dev/sg4: scsi2 channel=0 id=15 lun=0
     IBM       SERVERAID         1.00 [rmb=0 cmdq=0 pqual=0 pdev=0x3]
/dev/sg5: scsi2 channel=1 id=5 lun=0
     HP        Ultrium 3-SCSI    G37B [rmb=1 cmdq=0 pqual=0 pdev=0x1]
/dev/sg6: scsi2 channel=2 id=15 lun=0
     IBM       EXP400   S320     D110 [rmb=0 cmdq=0 pqual=0 pdev=0x3]

(that's a useful tool - cheers :-)

> Incidently, I have this entry in /etc/modprobe.conf:
>
> options scsi_mod max_luns=32

... and I think that's the difference - this was what Matt Brookover  
suggested as well :-)

I'm waiting for a new machine to arrive before I go fiddling with  
devices though, in case anything bad happens. The entire machine is  
SCSI, internal and external RAIDs, and I don't want there to be any  
surprises on a currently-active machine :-)

ATB, and thanks for the help :-)

Simon