Re: st driver doesn't seem to grok LTO partitioning

Le Fri, 18 Dec 2015 17:06:44 +0100
Emmanuel Florac <[email protected]> =C3=A9crivait:

>=20
> I'm trying to use mt to work with LTO-5 and bigger tapes. Switching
> partitions works:
>=20
> # tapeinfo -f /dev/sg1
> Product Type: Tape Drive
> Vendor ID: 'HP      '
> Product ID: 'Ultrium 5-SCSI  '
> Revision: 'Z61U'
> Attached Changer API: No
> SerialNumber: 'HU1249TP88'
> MinBlock: 1
> MaxBlock: 16777215
> SCSI ID: 1
> SCSI LUN: 0
> Ready: yes
> BufferedMode: yes
> Medium Type: Not Loaded
> Density Code: 0x58
> BlockSize: 0
> DataCompEnabled: yes
> DataCompCapable: yes
> DataDeCompEnabled: yes
> CompType: 0x1
> DeCompType: 0x1
> BOP: yes
> Block Position: 0
> Partition 0 Remaining Kbytes: 1459056
> Partition 0 Size in Kbytes: 1459056
> ActivePartition: 0
> EarlyWarningSize: 0
> NumPartitions: 1
> MaxPartitions: 1
> Partition0: 38
> Partition1: 1453
>=20
> # mt -f /dev/nst0 setpartition 1
>=20
>=20
> However "mt mkpartition" fails miserably:
>=20
> # mt -f /dev/nst0 mkpartition 1453
> /dev/nst0: Input/output error
>=20
> # dmesg | tail
> st 6:0:1:0: st0: Failed to read 65536 byte block with 256 byte
> transfer. st0: Sense Key : Illegal Request [current]=20
> st0: Add. Sense: Invalid field in parameter list
>=20
> Is this a limitation of mt or the st driver?
>=20

I'm replying to myself: this is very obviously a limitation of the st
driver. Checking st.c partition_tape() function, it looks like it only
knows of hardware from past century...=20

OTOH it seems that Cygwin does that properly... by using
CreateTapePartition, a windows kernel32.dll function. Argh. We'll have
to do the heavy lifting of SCSI commands by hand, then.

Where should we post an eventual patch, given that the linux-tape ML
looks like a ghost town? It would also be great to be able to support
more than 2 partitions (LTO-6 and 7 support 4), but that would require
patching the mt utility too, but I don't where it currently lives :)
Any hints welcome.

--=20
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Emmanuel Florac     |   Direction technique
                    |   Intellique
                    |	<[email protected]>
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