This is the information that we think that the operations staff currently needs to run the machine.

Today Gnosis does I/O only to disks and the Tymnet base and on rare occasions to tape.

If Gnosis is running on a virtual machine it is important to know that the Gnosis kernel notes disk errors and performs transient error recovery since it does SIO's to the disks.

The kernel provides error information to a program via the EREP key {(erep)}.

Gnosis does record data on different drives redundantly and can thus survive a dead drive. When the pack is brought online again, redundancy is automatically reestablished by rewriting the pack. This has caused severe temporary performance impairment.

The two drives of Gnosis should be on different channels or at least different controllers when possible.

Gnosis does checkpoints every few minutes. When Gnosis is IPL'd, it restarts from the most recent checkpoint. This happens without operator intervention. Some users have a key called "CHECKPOINT". If so the command "KEYCALL CHECKPOINT 0" causes a checkpoint to be done. If this is done just before taking the system down then everyone's last few minutes of work will be saved.

Gnosis under VM

Disabled Wait States and their Causes