How to interpret HP-UX device numbers from SCSI read and write errors in the syslog.

When SCSI read and write errors are logged in the syslog, the device number is written in hex. For example:

Jun 2 21:13:38 pdb01 vmunix: SCSI: Read error — dev: b 31 0x2b8400, errno: 126, resid: 8192,
Jun 2 21:13:39 pdb01 above message repeats 13 times
Jun 2 21:13:39 pdb01 vmunix: – dev: b 31 0x2b8400, errno: 126, resid: 8192,
Jun 2 21:13:39 pdb01 vmunix: blkno: 2895352, sectno: 5790704, offset: -1330126848, bcount: 8192.
Jun 2 21:13:52 pdb01 vmunix: SCSI: Write error — dev: b 31 0x038400, errno: 126, resid: 8192,
Jun 2 21:13:52 pdb01 vmunix: blkno: 5454416, sectno: 10908832, offset: 1290354688, bcount: 8192.

The numbers can be broken down as follows:

vmunix: SCSI: Write error — dev: b 31 0x2b8400

2b = Controller 43
8 = Target 8
4 = LUN 4

This translates to c43t8d4

vmunix: SCSI: Read error — dev: b 31 0x038400

03= Controller 3
8 = Target 8
4 = LUN 4

This translates to c3t8d4

There are 2 paths to the same Symmetrix device (091) that is logging the read and write errors:

/dev/rdsk/c3t8d4 :EMC :SYMMETRIX :5568 :32091000 :8838720
/dev/rdsk/c43t8d4 :EMC :SYMMETRIX :5568 :32091000 :8838720

In most cases when this type of error is seen against Symm devices, the issue is logical corruption and running fsck on the affected logical volumes or devices will solve the problem.

HP-UX also logs similar error messages when the LVM marks a device POWERFAILED

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