What is st0a & st0m for Linux ?

[Taohung]

Hello
My tape is HP DAT24.
My Linux is Redhat AS 4 x86_32bit.
I know that st0 is standard tape device name.
Default my st0 : enable rewind and compress.
In the /dev/*st0* => st0,st0a,st0m,nst0,nst0a,nst0m
"n" is no rewind.
What is the st0a & st0m ?

Thank you.

[Ivan Ferreira]

You can start with "man st". These devices differ in block size, compression, density, etc). The exact relationship I cannot tell.

[Matti_Kurkela]

The extra letters at the end of the tape device name can be used to specify the "mode" (usually, writing density) of the tape drive.

Different kinds of tape devices may allow different modes. The name without extra letter will specify the default mode, which usually is the highest writing density the device/tape can handle.

According to Documentation/devices.txt in Linux kernel documentation, /dev/st0 is "mode 0" or the default. /dev/st0l is "mode 1", /dev/st0m is "mode 2", /dev/st0a is "mode 3". The meaning of the mode numbers is dependent of the tape drive model.