Some general questions regarding barcode support:
Is anyone using a barcode reader enabled tape changer on FreeBSD?
I can't seem to find any good posts in the archive with example output
from "chio status -v" or "mtx status" on [Free]BSD w/ a working barcode
reader.
If you have one, could you post the output?
I was reading about ANSI/ISO standard labels. I guess the standard that
applies to (DLT for example) is "ANSI MH10.8M-1983 Code 39 (3 of 9)."
Some web sites offer printing of custom labels. Supposedly, the there is
an ASCII string a serial number printed out by chio(1) in the format
"<LABEL:SERIAL>".
There's also a separte remark FreeBSD chio man page regarding a 'voltag'
command:
--
voltag [-fca] <ET> <EU> [<label>] [<serial>]
Change volume tag for an element in the media changer. This com-
mand is only supported by few media changers. If it is not sup-
ported by a device, using this command will usually result in an
"Invalid Field in CDB" error message on the console.
--
I'm curious how this relates to the physical bar code placed on the tape?
Is this some sort of proprietary feature only supported by a select few
tape drives? Such as a small meta-label written to the first block the
tape similiar to the Amanda lablel? Jason Thorpe would probably know, but
I'm not going to bug him since he's busy hacking on the NetBSD kernel >:}.
The source code would also probably be revealing on this...
Supposedly, chio(1) can execute a command:
# chio move voltag VOLUME01 drive 0
And the synopsis states:
The voltag pseudo-element type allows the selection of
tapes by their volume tag (typically a barcode on the tape).
I'm also curious: does this imply that the loader has a small cache in
which barcode are in which slots/locations? Or is that cache in the
kernel? Obviously the loader has a small cache (perhaps in an nvram) of
which slots are occupied, OR the "chio status" sends a SCSI inquiry
command which polls those sensors in hardware.
...and finally, when chio(1) attempts to move a tape based on it's
"VOLTAG", is it using some cache of data from the loader nvram, or does
that imply that the barcode reader has to go out and re-read each tape's
label. Is the barcode label attached to the picker?
TIA,
~BAS
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