Library /sys$common/syshlp/SCA$NEUTRAL_HELP.HLB  —  SCA Topics, Reducing LOAD Time
    Loading an SCA library is a time-consuming operation. Here are
    suggestions for reducing LOAD time:

    o  Virtual I/O Cache facility

       SCA uses a large number of I/Os during LOAD. Disk caching can
       greatly reduce the number of I/Os, and improve performance.
       Your system manager can enable disk caching by setting the
       VBN_CACHE_S SYSGEN parameter.  Use SHOW MEMORY/CACHE to see
       whether disk caching is enabled.

    o  Batch loads

       Loading more than one module at a time is more efficient than
       loading modules separately. For example, use LOAD *.ANA.

    o  Multiple libraries

       With large software systems, it is a good idea to use more
       than one SCA library and load them all simultaneously. This
       can decrease the elapsed LOAD time considerably, especially
       if the libraries are on separate disks.  Using more than one
       CPU also helps, but not as dramatically, because SCA loading
       is mainly I/O intensive. For more information about how to use
       multiple libraries, see the help subtopics under Libraries.

    o  Choice of Disk

       SCA uses a large number of I/Os during LOAD. Loading an SCA
       library on a slow, heavily used, or badly fragmented disk
       causes the load to be less efficient.

    o  File Fragmentation and File Preallocation

       If your SCA library is larger than 20K blocks, you should
       consider preallocating the library when you create it.
       SCA extends the library file by 1000 blocks at a time, so for
       large libraries it extends the library many times, and this
       may cause your SCA library to be badly fragmented.

       Preallocate an SCA library with CREATE LIBRARY/SIZE=xxx, where
       xxx is the size of the library in disk blocks. Use the size of
       the SCA$EVENT.DAT file in your current SCA library directory as
       the value to the /SIZE qualifier.

       You can tell how badly your SCA libraries are fragmented by
       using the following command:

         $ DUMP/HEADER/BLOCK=COUNT=0 -
         _$ DISK:[sca_library_directory]SCA$EVENT.DAT

       The interesting portion of the output is the Map area. Each
       retrieval pointer represents a contiguous section on the disk.
       Because SCA extends SCA libraries 1000 blocks at a time, having
       a lot of retrieval pointers smaller than this is a strong
       indication that some defragmentation is needed.

    o  Using less disk space

       Use LOAD/DELETE to delete .ANA files after they are successfully
       loaded. This doesn't reduce LOAD time, but uses less disk space.
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