Prerequisites for suspending a Linux instance
Suspend and resume support checks for conditions that might prevent resuming a suspended Linux® instance. You cannot suspend a Linux instance unless all prerequisites are fulfilled.
The following prerequisites must be fulfilled regardless
of whether a Linux instance
runs directly in an LPAR or as a z/VM® guest:
- All tape device nodes must be closed and online tape drives must be unloaded.
- The Linux instance must not have used any hotplug memory since it was last booted.
- No program must be in a prolonged
uninterruptible sleep state.
Programs can assume this state while they are waiting for an outstanding I/O request to complete. Most I/O requests complete in a very short time and do not compromise suspend processing. An example of an I/O request that can take too long to complete is rewinding a tape.
For Linux on z/VM, the following additional
prerequisites must be fulfilled:
- No discontiguous saved segment (DCSS) device must be accessed
in exclusive-writable mode.
You must remove all DCSSs of segment types EW, SW, and EN by writing the DCSS name to the sysfs
removeattribute.You must remove all DCSSs of segment types SR and ER that are accessed in exclusive-writable mode or change their access mode to
shared. - All device nodes of the z/VM recording device driver must be closed.
- All device nodes of the z/VM unit record device driver must be closed.
- No watchdog timer must run and the watchdog device node must be closed.