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LTO-3 I/O error

CARTON
Occasional Advisor

LTO-3 I/O error

Hi,
my problem with MSL6060 / 2 LTO-3 drives :
"Cannot write to device - I/O error"
Tapes are full wih 20 - 40 Go, sometime less than 10 Go
Scsi3 configuration is OK, server=Win2003SP1
Firmware G25W upgraded to G54W: same error.
LTT says "parity errors with cabling issue"
Remote Manager show tape temperature over 60C when error occurs, could it be the cause?
5 REPLIES
Curtis Ballard
Honored Contributor

Re: LTO-3 I/O error

Look where the errors are pointing - if L&TT says you have a parity error then you almost certainly have a cabling or SCSI transciever issue. Parity errors that are intermittent are almost always cabling issues. A bad transciever usually means one lane in the cable will be bad and most bytes have parity errors so the drive won't function at all.

You don't say if one or both drives are causing problems. First thing to check is that 2 LTO-3 drives should never be on the same bus. Next thing to check is that the drive that is on the same bus as the library controller should have the cable from the host to the library controller, a jumper to the drive, then the terminator at the drive.

An internal temperature of 60C is higher than I like but that is measured at a hot location on the controller and the tape path temperatures are quite a bit lower. I think that an internal drive temp of 70C is about the limit for LTO-3.
CARTON
Occasional Advisor

Re: LTO-3 I/O error

Thanks for your answer;
as both drives have errors, and errors are more frequent when the two drives are writing, I aggree with your diagnostic. I will now check scsi cabling.
Jaclyn Rothe
Trusted Contributor

Re: LTO-3 I/O error

Additionally, IO errors can be caused when drives are daisy chained on one controller. For best performanace for LTO 3 drives (especially) each drive should be isolated on a non-RAID HBA PCI SCSI channel.

Here is some excellent documenation which explains why you can not totally fill all space on media tapes:

Tape Capacity Differences Prevent Remote Storage from Making Media Copies
http://support.microsoft.com/?kbid=266011

How File System and Disk Configuration Affect Backup Performance
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=lpg50032

Performance Assessment Testing:
http://www.hp.com/support/pat

HP Surestore/StorageWorks- Data Compression Information :
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=lpg50244&prodTypeId=12169&prodSeriesId=42846

HP StorageWorks - DLT and Ultrium Hardware vs. Software Compression
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=lpg50030&jumpid=reg_R1002_USEN

Jaclyn Rothe
Trusted Contributor

Re: LTO-3 I/O error

Additionally... on a side note... any time I see Windows 2003 I automatically assume RSM is causing a problem... please use the following document from Microsoft to fix majority of communication problems caused by RSM in 2003.

http://support.microsoft.com/kb/842411
CARTON
Occasional Advisor

Re: LTO-3 I/O error

Thank you for the links, this was helpfull.

The problem is solved now: I moved the scsi cables to the right and the power cables to left; nothing else change: errors was probably caused by interferences.