HP LTO 4 SCSI Design goals for LTO backup applications, TapeAlert, Diagnostic logs, Drive tests

See “Tape Capacity Log Page” under the LOG SENSE command in Chapter 3 of The SCSI Interface, Volume 3 of the HP LTO Ultrium Technical Reference Manual for more information.

While the reliability of tape products and applications is getting better all the time, problems do still occur. There are some very simple techniques that could be incorporated by application developers to simplify the process that a user must go through to resolve problems.

For additional information, see “Exception handling” on page 77.

TapeAlert

The TapeAlert facility in HP Ultrium drives allows applications to help avoid trouble by prompting the user to take remedial action, or in some cases, through the application automatically performing remedial actions itself.

For example, if the drive is experiencing trouble writing, the software can prompt the user to clean the heads, or, if there are several drives or an autoloader, automatically clean the heads without involving the user.

See “Monitoring the condition of the drive and media” on page 78 for more details.

Diagnostic logs

SCSI tape drives report problems in response to a REQUEST SENSE command from the host. If the backup application stores this information in a log file, it becomes significantly easier to troubleshoot problems, because the data can be used to pinpoint what is wrong.

Displaying drive information

Troubleshooting can also be simplified by giving users the ability to look at the drive’s firmware revision, and information about the host bus adapter. This information can be found by executing an INQUIRY command, and can then be displayed, or stored in a log file.

Drive tests

A basic read/write test should be included in a backup application to check the integrity of the hardware. This should also allow the user to scan the SCSI bus and to solve problems concerning the device setup and configuration.

Design goals for LTO backup applications

•Use large SCSI read/write transfer sizes (256 KB is recommended).

•Incorporate data compression control and report the compression ratios achieved.

•Consider where to store directory information depending on the nature of the application.

•Only use immediate WRITE FILEMARK commands, but avoid using other commands in immediate mode.

•Use Cartridge Memory information to measure tape quality before backing up starts.

•Use the TapeAlert log to prompt the user to take remedial action to avoid problems.

•Use “cleaning required” indicators in the software to either prompt the user or enable the library to use a cleaning cartridge to clean the drive heads.

•Allow users to set custom cleaning schedules.

HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 13 HP restricted