NAME

ml − RH11/RH70 - ML11 solid state disk

DESCRIPTION

The ML driver supports up to eight ML11 disk units on a separate RH11 or RH70 massbus disk controller.  If the ML11 is mixed with other disks, the HP or HM driver must be used. 

The ml?  refers to an entire ML11 unit as a single sequentially addressed file.  The size of each ML11 unit depends on the number of array modules installed.  There are 512 512-byte blocks per array module, for a maximum size of 8192 blocks per unit. 

Refer to the ULTRIX-11 System Management Guide for more information about logical disk names and disk sizes. 

The ML11 may be used for the swap device or perhaps mounted on /tmp.  The ML11 has switch-selectable transfer rates of 0.25 mb, 0.5 mb, 1.0 mb, and 2.0 mb per second. The following transfer rate restrictions apply:

 0.25 mball CPU’s
0.5  mball CPU’s
1.0  mbPDP 11/70 with RH70 only
2.0  mbNO PDP11 CPU’s

The ml files access the disk via the system’s normal buffering mechanism and may be read and written without regard to physical disk records.  A “raw” interface provides for direct transmission between the disk and the user’s read or write buffer.  A single read or write call results in exactly one I/O operation and therefore raw I/O is considerably more efficient when many words are transmitted.  The names of the raw files conventionally begin with an extra “r”.  In raw I/O the buffer must begin on a word boundary. 

RESTRICTIONS

In raw I/O read and write truncate file offsets to 512-byte block boundaries, and write writes data on the tail of incomplete blocks.  Thus, in programs that are likely to access raw devices, read, write, and lseek should always deal in 512-byte multiples. 

FILES

/dev/ml#, /dev/rml#

SEE ALSO

ULTRIX-11 System Management Guide
ULTRIX-11 Software Technical Description