User's Manual

280 Troubleshooting

To use buffered SCSI pass-through mode, uncomment the following line in trace.cfg, or add it if

necessary:

HSM_BEA_VERIFY_POSITION

This debugging variable cannot be used with the fsesystem --enable-dbg command. It can only be

specified in the trace.cfg file or used as environment variable.

The variable enables tape medium position check functionality of the Back End Agent (BEA). This BEA

feature decreases the probability of data loss in SCSI bus reset events. Such events are not reported to the

FSE system in certain cases and cannot be handled appropriately.

If you configure tape medium position check, BEA can check the position of an FSE tape medium during

write operations. By default, these checks are not performed. To enable or disable position checks for all

supported media families, set the HSM_BEA_VERIFY_POSITION environment variable to one of the

following:

• NEVER

This value disables tape medium position checks. The consequences of setting this value are improved

performance of tape write operations at the expense of reliability.

• ALWAYS

This value enables tape medium position checks for all supported media families.

Example

HSM_LA_SERIAL_UNLOAD

This variable makes unloads from drives to library slots serialized. By default the unloads (medium ejects)

are made in parallel.

Example

HSM_FRI_SAFETYBUF_TAPE

When migrating data, BEA checks for free space on tape to be able to copy the FRI file to the end of

medium. Since the drives only estimate the free space, there should be a safety buffer. This ensures that FRI

fits into the available space.

For LTO Ultrium and LTO Ultrium WORM media families, the suggested buffer size is 800 MB.

NOTE: The value is set in megabytes (only numeric characters are allowed).

Example

HSM_BEA_VERIFY_HEADER

Media header checks drop the performance of the LTO drives significantly. This variable enables the looser

verification of IDs in the volume header for tape media that do not have medium cartridge memory at the

time of migration. The IDs are verified only when the medium is exchanged.

The default value is “yes” or “true“. If this variable is set to "no" or "false" then the IDs in the header are