Data Areas
The directory exists on disk as 4K (page
size) records. TheVOL1 label (cylinder 0 track 0 record 3), on the volume containing
the directory, points to the directory. The
directory starts with the first available
record.
The firstUDIRBLOK is a dummy UDIRBLOK. Its UDIRDISP field points to the last UDIRBLOK in that record. The UDIRDASD field
peints to the nextUDIR record, or, if it
is the lastrecord, it contains zeros. The second UDIRBLOK in the first record points
to theUMACBLOK for that user, located in
the second record. In turn, theUMACBLOK points to the first UDEVBLOK for that user.
It is the second block in the second
record. The lastUDEVBLOK for this user has
a pointer of allzeros. The directory entry for the second user
consists of aUDIRBLOK in the first record
and associatedUMACBLOK, and UDEVBLOKs in
the second record.When a record becomes full, the chain continues into the next available record. When the directory is created, all UDIRBLOKs are grouped 169 blocks per
record. TheUMACBLOK and UDEVBLOKs are
sequentially chained into a separate
record. If the record becomes full before
the end of the chain, the chain overflows
into the next available record.
Theformula to find the number of records is: NO «BU+RM) X2) +ND + --------------
= NR
169170 NU is the number of user records. NM is the number of MDISK describing a v irtual disk
T-!isk)• cards
(netND is the total number of MDISK (describing T-Disk sFace), SPOOL, LINK, SPECIAL, CCNSCLE, and DEDICATE
cards;;; DR is the total number of records used.
To find the number of cylinders, divide
the total number of records by 32for 2314/2319 devices, by 57 for 3330 series devices, or by 24 for 3340 and 2305 series
devices. To ensure that a new directory
will not overlap an existing directory,
allow space for two directories or allocate
a new directory eachtile the directory is created.
The following data areasare used by the
directory program:• The UD!VBLOK (user device block), built
in theUDEVBLOK or UeACELCK buffer. • The urIRBLOK (user directory block),
built in theDIRBLOK buffer. • The UMACBLOK (user machine block), built
in theUMACBLCK buffer.
These data areas, as well as a figure
showing the user directeryfermat and
relationship of the above blocks,
described in theltV37.Q ]!!! £2!tt;Q! ck§ ic • Chapter q. tMKDIR--The Directcry program the are !l!.Q n1 J ,
The directory exists on disk as 4K (page
size) records. The
the directory, points to the directory. The
directory starts with the first available
record.
The first
peints to the next
is the last
to the
the second record. In turn, the
It is the second block in the second
record. The last
a pointer of all
consists of a
and associated
the second record.
record. The
sequentially chained into a separate
record. If the record becomes full before
the end of the chain, the chain overflows
into the next available record.
The
= NR
169
T-!isk)
(net
cards
To find the number of cylinders, divide
the total number of records by 32
devices. To ensure that a new directory
will not overlap an existing directory,
allow space for two directories or allocate
a new directory each
The following data areas
directory program:
in the
built in the
in the
These data areas, as well as a figure
showing the user directery
relationship of the above blocks,
described in the