LTO type M cartridge (M8)
The LTO program introduced a new capability with LTO8 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 LTO7 format.
Such a cartridge is called an LTO7 initialized LTO Type M cartridge. These LTO Type M cartridges are identifiable by using an automation bar code label that ends with the last 2 characters “M8”.
| Cartridge/Density type | Bar code label | Cartridge Packaging/Silkscreen labeling | Native capacity | Tape Drive compatibility |
|---|---|---|---|---|
| L9 | xxxxxxL9 | LTO Ultrium 9 | 18 TB | LTO9 |
| L8 | xxxxxxL8 | LTO Ultrium 8 | 12 TB | LTO8 |
| M8 | xxxxxxM8 | LTO Ultrium 7 | 9 TB | LTO8 |
| L7 | xxxxxxL7 | LTO Ultrium 7 | 6 TB | LTO7, LTO8 |
From now on, these cartridges are referred to as L9. L8, M8, and L7.
Only new, unused LTO Ultrium 7 cartridges can be initialized as M8 cartridges. When a cartridge is initialized as M8, it cannot be changed back to L7. Initialized M8 cartridges can be written and read only in an LTO8 tape drive. LTO7 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 uninitialized M8 data cartridges (M8 WORM cartridges are not supported). For either option, the bar code label is included. However, the uninitialized M8 data cartridge must first be initialized in tape libraries that support the automatic initialization of uninitialized M8 cartridges while under the control of ISV applications that recognize the “M8” bar code 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 then establishes the density of the media.
If an uninitialized M8 cartridge is not initialized in a tape library that supports uninitialized M8 cartridges, then the cartridge might inadvertently and silently be initialized at the L7 density (that is, at a 6 TB native capacity) even if the bar code label states “M8”. This action might occur with the usage of a non LTO8 tape drive, a stand-alone LTO7 tape drive, a stand-alone LTO8 tape drive, earlier LTO8 tape drive firmware, or earlier ISV software that does not recognize that M8 cartridges must be mounted only in LTO8 tape drives. M8 cartridges that are inadvertently initialized at the L7 density can continue to be read and written in LTO7 and LTO8 tape drives. However, they remain limited to the 6 TB native capacity.
In any tape product with M8 cartridges, the minimum LTO8 tape drive firmware version is HB82.