1  SET

   Controls XFC's statistics collection feature(s).

2  TRACE

   Controls the types of events that will be recorded by XFC's trace
   facility and initializes the trace structures (to eliminate already-
   recorded events).

3  Description

   The events that can be traced are organized into five categories
   (Extent/Hash, Init/Common/Sys, Lock, LRU/Mem/MemMgt, and Read/Write),
   which correspond to the organization of the XFC software
   architecture.  Within each type, the traceable events are organized
   by level of importance.  With the /SELECT qualifier, the user can
   select events to trace by type and level-within-type.  With the /MASK 
   qualifier, the user can select arbitrary (groups of) events to be
   traced.

   Format

     SET TRACE [/SELECT= | /MASK=] [/RESET]

3  Qualifiers

/SELECT

     /SELECT={TYPE:type, LEVEL:level}

   Allows the user to control what is traced by named
   category.  The value list should consist of paired
   type and level specifications, with the type preceding
   the level.  If a TYPE specifier is not followed by a
   level specifier, tracing for that type will be set to
   the default level.  If a LEVEL specifier is not preceded
   by a TYPE specifier, the level will be set for all types.

   The default tracing level is:
           1 - standard XFC image
           4 - MON image
           4 - DEBUG image
   
   An attempt to set the level above the maximum for any type
   results in a warning and the level being set to the maximum.

   The trace types and level selected in the value list of
   one instance of the /SELECT qualifier enables tracing of
   those events and disables all others.  (If multiple
   SET TRACE/SELECT commands are used, only the selections of
   the last will take effect.)

   The LOCK category has 6 possible levels (1 through 6).
   All other categories have 4 possible levels (1 through 4).


/MASK

     /MASK=bitmask

   Allows the user to select individual trace types by the bit
   positions in bitmask that are set to 1.  The /MASK qualifier
   is incompatible with the /SELECT qualifier.

   The bit positions are as follows:

        0 - Extent/Hash Level 1
        1 - Extent/Hash Level 2
        2 - Extent/Hash Level 3
        3 - Extent/Hash Level 4
        4 - Init/Common/Sys Level 1
        5 - Init/Common/Sys Level 2
        6 - Init/Common/Sys Level 3
        7 - Init/Common/Sys Level 4
        8 - LRU/Mem/MemMgt Level 1
        9 - LRU/Mem/MemMgt Level 2
       10 - LRU/Mem/MemMgt Level 3
       11 - LRU/Mem/MemMgt Level 4
       12 - Read/Write Level 1
       13 - Read/Write Level 2
       14 - Read/Write Level 3
       15 - Read/Write Level 4
       16 - (Reserved)
       17 - (Reserved)
       18 - (Reserved)
       19 - (Reserved)
       20 - (Reserved)
       21 - (Reserved)
       22 - (Reserved)
       23 - (Reserved)
       24 - Lock Level 1
       25 - Lock Level 2
       26 - Lock Level 3
       27 - Lock Level 4
       28 - Lock Level 5
       29 - Lock Level 6
       30 - (Reserved)
       31 - (Reserved)


/RESET

   Initializes the trace buffer to eliminate all already-traced
   events.