X is there a way to know what M-?? files exist in the <mount-point>/.tags. dir?
X Sometimes there is a M-6 and M-18, sometimes and M-12, ...
X I use showfile to check if these files exist.
X Apparently you can see how many BMT extends you have through these files.
sys_check knows how to do this. It will run the showfile and actually
print all of that out for you.
If you really want to know you can always reverse engineer the script to
see what it does.
But in a nut shell, there is one BMT for every volume in the domain. Do
a showfdmn and get the list of volumes. Multiply the volume number
shown by 6. This is good for DVN 3 on-disk structures. If you have the
newer DVN 4 on-disk structure (released in Tru64 UNIX v5.0), then you
really don't care because the BMT can have an unlimited number of
extents (and the 6, 12, 18 numbers changed to something else).