gautam79
New User
Joined: 30 Aug 2006
Posts: 11
Location: India
|
|
|
|
Hi,
Basic Checkpointing:
All programs can use the Basic method, it is the only checkpoint method available to MPP?S, or online programs. The application program must provide its own method of restarting, because the extended restart call is not supported. Neither OS/VS nor GSAM files are supported with the Basic checkpoint method. It is your responsibility to provide an 8-character checkpoint ID and to increment it as processing dictates. A message is sent to the master console, as well as to the JES log, with the checkpoint ID and a date and time stamp. You will need this information, if a checkpoint restart becomes necessary. A major disadvantage of the Basic checkpoint method is that you cannot change anything in your program prior to restarting.
Thus, it can be used in DL/I, BMP and MPP program. IMS resources are released. Database changes are permanent. Programmer must provide restart logic to restore variables and database position.
Symbolic Checkpointing:
Only BMP and batch programs can use this method. Up to seven I/O areas can be saved with Symbolic checkpointing. Symbolic checkpointing uses the extended restart call. For information to be saved during execution, and then later restored upon restarting, the variables will be saved in the log file every time a checkpoint call is issued. Then, when the program is restarted with the extended restart (XRST) call, the variables will be restored from the log file created during the first execution.If a restart was requested, the XRST call automatically restores all of the variables you declared in the checkpoint area. It also restores the position in all data bases and GSAM files at the current position when that checkpoint was taken. (IMS does this by issuing internal GU calls).
I think this is a big reply but might answer most of your queries.
[/u] |
|
