MPE/iX 5.5 Operating System Limits

At checkpoint time, all active transactions are examined. Transactions spanning one
checkpoint will be included in the checkpoint record; transactions spanning two
checkpoints will be copied forward. If a long transaction exists, a temporary object will
be created to hold the physical address of all chained log records for long transactions.
The physical log address list will be sorted and then be moved to the next half of log file
in ascending order. This algorithm reduces the size of these running transactions,
consequently reduces the stalled transaction risk. The number of copy forward user
transaction records per log file has been estimated to 48000.
The user process will be aborted if one of the three limits is reached: 1. the maximum
number of time a transaction was copied forward gets bigger than 100. 2. the maximum
size of a transaction gets bigger than 4 Mbytes. 3. the size of all the user transactions gets
bigger than log_file_size/2.
(5) XM logfile/Volset restrictions
As there is one XM system log file per volumeset, and the number of volumesets per
system is limited to 255, the maximum number of XM system logfile is 255.
MPE/iX 5.5 Data Communications Limits
The focus of this sections is the software limits imposed on the common Networking
products found on the MPE/iX operating system. These limits are current as of release
5.5 and all attempts have been made to provide information as accurate as possible.
While all attempts have been made to keep this document up-to-date with the latest
release of the operating system, it is possible that patches or new product introductions
may not be reflected in this information.
Structure of this section
You will notice that this section is divided into functional areas. The functional areas
represented in this version of the document include the following:
Network Services and Transport Limits
Virtual Terminal (VT) Limits
Terminal and Serial Printer I/O limits