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Add Support for LTO7M8 tapes. #71
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According to the scsi ref for LTO8, there is no separate type value. To identify it as a higher volume capacity when used on the later gen drive, they have borrowed the volume personality feature from 3592 as that always had this ability to increase capacity of older generation tapes in new drives. From ref document The volume personality parameter contains an ASCII string to identify the combination of physical volume type and density formatted on the medium. The intent is to provide a designator sufficient for successful volume |
The medium type should be the same as LTO-7 (78h) - This is byte[2] in the Mode Parameter Header for Mode Select. |
It is a one way change once you write as LTO7 it cannot be changed to an M8 and vice versa and an LTO7 drive cannot read the M8 tapes. |
I'm assuming this LTO-8M a write at BOT only type of change. |
Checking out 'compatibility' section on Wikipedia is answering my questions. The IBM SCSI reference I have is as clear as mud. |
And the HPE LTO-7 cartridge initialised as Type M media is a gold mine..
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I was previously looking for the scsi commands to set the lto8 drive to the m8 mode so new lto7 tapes would be initialised as an M8 but no luck there. I did find a reference to it on the releases notes for the sl8500 firmware update for M8 and said that ADI mode has to be on so I guess their setting it through the ethernet or rs422 connections via the library and that also be how their getting the error returned also. |
The HPE document did state that M8 media can not be initialised by stand-alone drives (but stand alone can read the M8 format). Hence it can not be a simple SCSI OP code - otherwise the OP code could be sent to the stand-alone drive. Or perhaps this is to prevent media with 'L7' being initialised as M8, as the media mount rules of the library will/should not permit the mount. This may require a re-think of mhVTL mount logic. Currently all media can be moved into any drive type - the drive rejects any format not suitable - even inserting 4mm into LTO (as there is no physical barriers in a virtual library). As an immediate work-around, update 'edit_tape' & 'mktape' commands to create M8 type media. i.e. no automation of the 'conversion' process. |
Thanks for the comments. I will have a read through and submit an update later tonight. Perhaps I should have submitted the T10KD cartridge PR first! |
That reminds me the T10k is also missing the Sport cartridges. |
Just submitted #72 |
As per : https://www.ibm.com/docs/en/ts4500-tape-library?topic=media-lto-type-m-cartridge-m8, |
Updated Media type to the correct value. |
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Is this 'media_type_lto7m8' a valid media type ?
I mean, in real life, it is simply an LTO7 cartridge initialised in an LTO8 drive.
Hence, shouldn't the media_type be LTO7.
Nit-picking here as both LTO7 and LTO7m8 have the same media type value - but why have them separated - simply use the LTO7.
The different medium_density_code is the difference between the LTO7 cartridge being initialised in an LTO7 or LTO8 drive.
LTO7M8 tapes are LTO7 cartridges written by LTO8 drives. This enables 9TB to be stored on a tape designed for 6TB.
I have added these , but I am unsure of the media_type_lto7m8_data value in usr/vtltape.h.
Note: LTO7M8 does NOT support WORM style tapes.