ultrix man page for drum

drum(4) 						     Kernel Interfaces Manual							   drum(4)

Name
       drum - paging device

Description
       This  file refers to the paging device in use by the system.  This may actually be a subdevice of one of the disk drivers, but, in a system
       with paging interleaved across multiple disk drives, it provides an indirect driver for the multiple drives.

Restrictions
       Reads from the drum are not allowed across the interleaving boundaries.	Because these occur only every .5Mbytes or  so,  and  because  the
       system never allocates blocks across the boundary, this is usually not a problem.

Files
See Also
       MAKEDEV(8)

																	   drum(4)