LTO Type M cartridge (M8)
The LTO program introduced a new capability with LTO
8 tape drives: the ability to write 9 TB (native) on a brand new LTO Ultrium 7 cartridge instead of
6 TB (native) as specified by the LTO 7 format. Such a cartridge is called an LTO Ultrium 7
cartridge initialized as Type M media (M8). These cartridges are identifiable by using an automation
barcode label ending with the characters M8.
| Cartridge/density type | Barcode label | Cartridge packaging/silkscreen labeling | Native capacity | Tape drive compatibility |
|---|---|---|---|---|
| L8 | xxxxxxL8 | LTO Ultrium 8 | 12 TB | LTO 8 |
| M8 | xxxxxxM8 | LTO Ultrium 7 | 9 TB | LTO 8 |
| L7 | xxxxxxL7 | LTO Ultrium 7 | 6 TB | LTO 7, LTO 8 |
Hereafter, these cartridges will be referred to as L8, M8, and L7, respectively.
Only new, unused LTO Ultrium 7 cartridges can be initialized as M8 cartridges. Once a cartridge is initialized as M8, it cannot be changed back to L7. Initialized M8 cartridges can only be written and read in an LTO 8 tape drive; LTO 7 tape drives cannot read initialized M8 cartridges.
M8 cartridges can be purchased as either pre-initialized (also referred to as “labeled and
initialized”) M8 data cartridges or un-initialized M8 data cartridges (M8 WORM cartridges are not
supported). For either option, the barcode label is included; however, the un-initialized M8 data
cartridge must first be initialized in tape libraries that support the automatic initialization of
un-initialized M8 cartridges while under the control of ISV applications that recognize the
M8 barcode label.
A tape cartridge is initialized when it is first loaded into a compatible tape drive and data is written by the ISV application at the beginning of tape (sometimes referred to as "labeling a tape" or "writing from BOT"). The tape drive establishes the density of the media at that time.
If an un-initialized M8 cartridge is not initialized in a tape library that supports
un-initialized M8 cartridges, then the cartridge may inadvertently and silently be initialized at
the L7 density (i.e., at a 6 TB native capacity) even if the barcode label states
M8. This could occur with the usage of non-TS4500 tape libraries, stand-alone LTO 7
tape drives, stand-alone LTO 8 tape drives, down-level LTO 8 tape drive firmware, down-level TS4500
tape library firmware, or down-level ISV software that does not recognize that M8 cartridges should
only be mounted in LTO 8 tape drives. M8 cartridges that are inadvertently initialized at the L7
density can continue to be read and written in LTO 7 and LTO 8 tape drives; however, they will
remain limited to the 6 TB native capacity.
TS4500 tape library firmware version 1.4.1.2 added support for un-initialized M8 cartridges in addition to support for pre-initialized M8 cartridges. The TS3500 tape library only supports pre-initialized M8 cartridges. In any tape product with M8 cartridges, the minimum LTO 8 tape drive firmware version is HB82.