US 4,608,688 A · Processing system tolerant of loss of access to secondary storage

Abstract

In a processing system (100) that swaps processes between a main memory (114 or 124) and a pair of duplicated disks (132, 142), system processing capability is protected against loss of access to both system-essential duplicated disks. Upon loss of access to one duplicated disk, processes designed as essential to the system's operation and not resident in the main memory are swapped into the main memory from the other duplicated disk. All essential processes are then locked into the main memory to prevent their removal therefrom. Thus the essential processes remain accessible to the processing system even upon loss of access to both of the disks. Upon loss of access to both of the disks, the system may undergo reconfiguration in an attempt to regain access to at least one of the disks. If reconfiguration fails, non-essential processes are killed and the system continues processing using only the essential processes. Upon restoration of access to one of the disks, the restored disk is initialized from tape and the system is then bootstrapped from the restored disk, and normal processing is resumed. Upon restoration of access to the second disk, the second disk is repopulated from the first disk and the essential processes are unlocked from the main memory.

Claims38

Dependent claims

In a processing system that includes

a plurality of secondary memory means each storing a replica of information for use by the processing system, including designated information,
main memory means for storing selected portions of the information, and
means for transferring portions of the information between the main memory means and the secondary memory means,
a method of protecting at least some system operating capability against loss of information transfer of secondary capability between the main memory means and the plurality memory means, comprising the steps of:
detecting loss of information transfer capability between the main memory means and all but at least one of the secondary memory means;
in response storing all designated information in the main memory means;
and
preventing removal of the designated information from the main memory means while permitting information transfer between the main memory means and the at least one secondary memory means and prior to loss of information transfer capability between the main memory means and the at least one secondary memory means;
whereby the designated information remains available to the process system in the main memory means upon loss of information transfer capability between the main memory means and the plurality of secondary memory means.

6 more elements

In a processing system that includes

a pair of secondary memory subsystems each storing a copy of data and programs for use by the processing system, including data and programs designated essential to system operation,
a main memory for storing selected ones of the data and programs, and
control means for transferring data and programs between the main memory and the secondary memory subsystems,
a method of protecting system processing capability against loss of data and program transfer capability between the main memory and both secondary memory subsystems, comprising the steps of:
detecting loss of data and program transfer capability between the main memory and one of the secondary memory subsystems;
in response transferring such designated data and programs as are not stored in the main memory from the other of the secondary memory subsystems into the main memory;
locking the designated data and programs into the main memory to prevent their removal from the main memory to maintain the designated programs and data available in the main memory to the processing system to continue processing therewith should data and program transfer capability between the main memory and both of the secondary memory subsystems be lost;
detecting loss of data and program transfer capability between the main memory and both of the secondary memory subsystems;
and
in response limiting processing to execution of the designated programs, using the designated data and selectively other data available from sources other than the secondary memory subsystems.

7 more elements

In a processing system that includes

a first and a second disk memory each storing a copy of processes for use by the processing system, including processes designated essential to system operation,
a main memory for storing selected processes requested by the processing system for use,
a first controller for accessing the first disk memory to swap processes between the main memory and the first disk memory, and
a second controller for accessing the second disk memory to swap processes between the main memory and the second disk memory,
a method of protecting system processing capability against loss of access to both disk memories, comprising the steps of:
detecting loss of access to the first disk memory;
in response swapping such of the essential processes as are not stored in the main memory from the second disck memory into the main memory;
locking the essential processes into the main memory to prevent their removal from the main memory to maintain the essential processes accessible in the main memory to the processing system upon loss of access to both disk memories;
detecting loss of access to both disk memories;
and
in response limiting processing to the execution of the essential processes, including terminating processes not designated essential stored in the main memory.

8 more elements

In a processing system that includes

a first and a second processor arranged in an active-inactive configuration, respectively,
each processor comprising a central processing unit for executing processes, a main memory coupled to the central processing unit for storing selected processes requested by the processing unit for use, and a first and a second direct memory access controller coupled to the main memory unit,
the processors being communicatively coupled to each other by means for selectively keeping the contents of the main memories duplicated,
the processing system further including means for reconfiguring the system,
a first and a second disk memory each for storing a copy of processes, including the selected processes, for use by the processing system, including processes designated essential to system operation, the first direct memory access controller of each processor being coupled for access to the first disk memory and the second direct memory access controller of each processor being coupled for access to the second disk memory to enable each controller to swap processes between the associated main memory and the associated disk memory, and
at least one tape memory for storing an initial version of the processes stored by the disk memories, the tape memory coupled for access to at least one of the direct memory access controllers,
a method of protecting the processing capability of the system against loss of access to both disk memories, comprising the steps of:
detecting loss of access from the active processor to the first disk memory;
in response swapping such of the essential processes as are not stored in the active processor's main memory from the second disk memory into the active processor's main memory;
and
locking the essential processes into the active processor's main memory to prevent removal thereof from the active processor's main memory;
detecting loss of access from the active processor to both disk memories;
in response attempting to reconfigure the system to gain access from at least one of the processors to at least one of the disk memories;
resuming normal processing while maintaining the essential processes locked in the active processor's main memory if access to at least one of the disk memories is gained by the attempted reconfiguration;
limiting processing to the execution of the essential processes, including terminating processes not designated essential stored in the active processor's main memory, if access to at least one disk memory is not gained by the attempted reconfiguration;
receiving notice of manual restoral of access by the active processor to one of the disk memories, if access to at least one disk memory has not previously been gained by the attempted reconfiguration;
in response to the notice, copying into the one disk memory the initial version of the processes from the tape memory;
further in response to the notice, swapping the initial version of the essential processes from the one disk memory into the active processor's main memory;
further in response to the notice, ceasing limitation of processing while maintaining the essential processes locked in the active processor's main memory;
receiving notice of restoral of access to both disk memories;
in response copying contents of the one disk memory into the other disk memory;
and
unlocking the essential processes from the active processor's main memory to enable their removal from the active processor's main memory.

20 more elements

A processing system comprising

a plurality of secondary memory means each for storing a replica of information for use by the processing system, including designated information;
main memory means for storing selected portions of the information;
means for transferring the selected portion of the information between the main memory means and the secondary memory means;
means cooperative with the transferring means for detecting loss of information transfer capability between the main memory means and a secondary memory means;
means cooperative with the transferring means and responsive to the loss-detecting means for storing all designated information in the main memory means, upon loss of information transfer capability between the main memory means and all but at least one secondary memory means;
means responsive to the loss-detecting means for preventing removal of the designated information from the main memory means upon loss of information transfer capability between the main memory means and all but at least one secondary memory means to maintain the designated information available to the processing system in the main memory means upon loss of information transfer capability between the main memory means and all of the secondary memory means;
and
means responsive to the loss-detecting means for limiting system operation to the use of the designated information, upon loss of information transfer capability between the main memory means and all of the secondary memory means.

5 more elements

A processing system tolerant of loss of access to disk memories, comprising:

a pair of disk memories each for storing a copy of processes for use by the processing system, including processes designated essential to system operation;
a main memory for storing selected ones of the processes;
transfer means for transferring processes between the main memory and the disk memories;
means cooperative with the transfer means for detecting loss of process transfer capability between the main memory and a disk memory;
means for detecting restoral of process transfer capability between the main memory and a disk memory;
means for selectively locking the designated processes into the main memory to prevent their removal from the main memory;
and
control means responsive to the loss-detecting means for causing the transfer means to transfer such designated processes as are not stored in the main memory from the other of the disk memories into the main memory and for causing the locking means to lock the designated processes into the main memory, upon detection of loss of process transfer capability between the main memory and one of the disk memories, to maintain the designated processes available in the main memory to the processing system to continue processing therewith should process transfer capability between the main memory and both of the disk memories be lost, the control means further responsive to the restoral-detecting means for causing the locking means to unlock the designated processes in the main memory to enable their transfer from the main memory, upon detection of restoral of process transfer capability between the main memory and both of the disk memories.

5 more elements

A processing system tolerant of loss of access to disk memories, comprising:

a pair of disk memories each for storing a copy of processes for use by the processing system, including processes designated essential to system operation;
a main memory for storing selected ones of the processes;
transfer means for transferring processes between the main memory and the disk memories;
means cooperative with the transfer means for detecting loss of process transfer capability between the main memory and a disk memory;
means for selectively locking the designated processes into the main memory to prevent their removal from the main memory;
and
control means responsive to the loss-detecting means for causing the transfer means to transfer such designated processes as are not stored in the main memory from the other of the disk memories into the main memory and for causing the locking means to lock the designated processes into the main memory, upon detection of loss of process transfer capability between the main memory and one of the disk memories, to maintain the designated processes available in the main memory to the processing system to continue processing therewith should process transfer capability between the main memory and both of the disk memories be lost, the control means further responsive to the loss-detecting means for limiting processing to execution of the designated processes, upon detection of loss of process transfer capability between the main memory and both of the disk memories.

4 more elements

Dependencies are inferred from the claim text.

Processing system tolerant of loss of access to secondary storage

Life of this patent

Processing system tolerant of loss of access to secondary storage

Life of this patent

Abstract

Claims38