There are different means you can use to try to decrease LOAD
time. Listed below are a few guidelines that may help you reduce
LOAD time:
o Loading an SCA library for a software system is a time
consuming operation and should be done in batch. Loading
more than one module at a time is more efficient than loading
modules separately. Using LOAD *.ANA is a common method for
loading multiple modules. You use LOAD/DELETE to clean up .ANA
files after they are loaded successfully and to use a little
less disk space during the load.
o With large software systems, it is a good idea to use more
than one SCA library and load them all simultaneously. This
can lessen the elapsed LOAD time considerbly. You should be
able to load several libraries simultaneously on a single
disk. Additionally, using more than one CPU to do your loads
also helps, but SCA loading is mainly I/O intensive. For more
information about how to use multiple libraries, see the help
subtopics under Libraries.
o Once your SCA library starts getting above 20K blocks, you
should consider preallocating the library when you create it.
SCA currently extends the library file by 1000 blocks at a
time, so for large libraries it frequently extends the library.
You can preallocate an SCA library by specifying 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.
o SCA uses a large number of I/Os during LOAD. Loading an SCA
library on a heavily used or badly fragmented disk causes the
load to be less efficient.
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.