HP LTO3 - Operates at Reduced Transfer Rate When Daisy Chained to SL500 Tape Library

Asset ID:	1-71-1002505.1
Update Date:	2011-04-14
Keywords:

Solution Type Technical Instruction Sure

Solution 1002505.1 : HP LTO3 - Operates at Reduced Transfer Rate When Daisy Chained to SL500 Tape Library

Applies to:

Sun StorageTek SL500 Modular Library System - Version: Not Applicable and later [Release: N/A and later]
HP LTO3 Tape Drive - Version: Not Applicable and later [Release: N/A and later]
All Platforms
Checked for relevance on 28-Jan-2011.

Goal

SCSI interface HP LTO3 tape drives may operate at reduced transfer rates or generate SCSI errors when daisy chained to the SL500 Tape Library controller on a single SCSI bus.

Solution

Steps to Follow
With HP LTO3 drives daisy chained to a SL500 library, the drives will negotiate to a lower transfer rate during write/read operation. In the var/adm/messages file you will see "Target 3 reverting to async. mode".
On some occasions, commands may be aborted. When this occurs, the error "Sense Key: Aborted Command" with an ASC 0x47 ASCQ 0x3 will be seen.

The code OBx4703 is "Information Unit CRC error detected, the drive has detected a CRC error during the command IU or data out phase." This issue has also been seen when three or more HP LTO3 drives are daisy chained on the same bus.

When this issue occurs, the messages file will look similar to the following:

Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.warning] WARNING: /pci@7c0/pci@0/pci@1/pci@0,2/scsi@1 (mpt3):
Aug 31 09:02:55 rss57 Target 3 reverting to async. mode
Aug 31 09:02:55 rss57 mpt: [ID 675377 kern.warning] WARNING: ID[SUNWpd.mpt.sync_wide_backoff.6013]
Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.warning] WARNING: /pci@7c0/pci@0/pci@1/pci@0,2/scsi@1/st@3,0 (st14):
Aug 31 09:02:55 rss57 Error for Command: write Error Level: Fatal
Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.notice] Requested Block: 0 Error Block: 0
Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.notice] Vendor: HP Serial Number: 13:40 rss57 genunix: [ID 936769 kern.notice] px_pci6 is /pci@7c0/pci@0
Aug 30 14:13:40 rss57 px_pci: [ID 37
Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.notice] Sense Key: Aborted Command
Aug 31 09:02:55 rss57 scsi: [ID 107833 kern.notice] ASC: 0x47 (information unit iucrc error detected), ASCQ: 0x3, FRU: 0x013:40 rss57 px_pci: [ID 370704 kern.notice] PCI-device: pci@0,2, px_pci10

Corrective Action:

At this time, isolate the SL500 SCSI controller on its own SCSI bus and do not daisy chain more that two HP LTO 3 drives together.