reading tape barcodes from TSM

[gshiman]

I found no way of querying tape barcodes from TSM backup catalog. It allows one to query tape labels, but no barcodes. Does it mean that TSM doesn't store tape barcodes?

I understand that LABEL LIBVolume command allows setting tape label to barcode (via LABELSource=Barcode option), but the other two values of that option (Prompt and Vollist) allow generating tape labels that differ from tape barcodes. That makes it possible for internal tape label to differ from the tape's barcode. But then how TSM will identify tape media to the library using such mismatched tape label?

The fact that AIDIT LIBRARY command talks about synchronizing inventory of library with that of library client (I assume it means TSM storage agent by that) and will use barcode, if available, as a tape label, doesn't help, as it will not do the right thing when tape label is not the same as the barcode (see above). Even if AUDIT LIBRARY records that value as tapelabel in TSM catalog.

Having barcodes recorded in TSM catalog would solve this issue, but I found no indication that they are recorded. I find it hard to believe, as without barcode TSM won't be able to tell to the library which tape it wants to access. Reading internal tape label will be very inefficient.

I use TSM 6.3.3 and didn't find barcodes returned by any of TSM command and didn't find barcodes in any of the db2 tables. That allows for two possibilities:
1) Setting tape labels to barcode is recommended practice and if that isn't done, this needs to be fixed by relabeling tape or changing its barcode
2) Barcodes are stored by storage agent outside of the backup catalog

I find 2) less likely, but decided to post the question to find out.

Thanks in advance,
George

 

[moon-buddy]

I understand that LABEL LIBVolume command allows setting tape label to barcode (via LABELSource=Barcode option), but the other two values of that option (Prompt and Vollist) allow generating tape labels that differ from tape barcodes. That makes it possible for internal tape label to differ from the tape's barcode. But then how TSM will identify tape media to the library using such mismatched tape label?

While there is a the option of defining the tape label via 'prompt', this should not be used in libraries that have barcode readers. As far as I remember, if a barcode reader is present and a different label is specified to write on the physical tape, the library will not do so and sends out an error message.

The 'file list' behaves differently. If a 'search=yes' is specified, TSM writes the tape label based on the list and in reference to the barcode.

These are what I remember. I have not labeled tapes without barcode readers for years. I used 'prompt' some 10 years or so with a manual tape drive,

 

[gshiman]

[QUOTE="The 'file list' behaves differently. If a 'search=yes' is specified, TSM writes the tape label based on the list and in reference to the barcode.[/QUOTE]

Thanks for clarification, Ed.

With "search=yes" volume labels specified by VOLRange or VOLList options are written to tapes that have readable barcode and don't have volume label. That will allow for different volume label to be written to tape than its barcode. That is consistent with the fact that tape label can have up to 32 alphanumeric characters, while barcode is limited by 8 characters. In that case TSM will determine tape's slot number (aka element) during AUDIT command and will use it to identify tape in the library, which is the third explanation of why TSM doesn't record barcodes, to continue list at the end of my original post:

3) TSM uses element number determined during library inventory (AUDIT command) to identify tape having given volume label

I still would like to receive definite answer to whether TSM stores barcodes (in the form of the mapping of volume label to barcode), as that would allow direct access to tape volume in the library, not requiring expensive library inventory operation.

Do you happen to know the answer to that?


The only argument against recording barcodes in TSM catalog, I can think of, is desire to avoid dealing with barcode reader issues in support calls.