US 5,193,154 A · Buffered peripheral system and method for backing up and retrieving data to and from backup memory device

Abstract

A buffered peripheral system comprises a backup memory and a primary control unit which has a buffer memory for temporarily storing a copy of the contents of a buffer memory which stores data to be written to a peripheral device and a control device for issuing a command necessary to write the block stored in the buffer memory device to the peripheral device. The primary control unit also includes a recording device for recording the block number corresponding to the block which was most recently written to the peripheral device. The blocks of data which have been written to the peripheral device is then deleted from the backup memory to make room for storing further blocks of data. The system further has a backup control unit substantially identical to the primary control unit. Only the primary control unit normally operates to control the writing to the peripheral device. Upon detection of the failure of the buffer memory in the primary control unit, the backup control unit completes the operation of writing to the peripheral device by retrieving the blocks of data to be written to the peripheral device from the backup memory device using the block number information.

Claims5

Dependent claims

A buffered peripheral system which is connected to a central processing unit through a channelling means, comprising:

a peripheral device;
a backup memory means for storing blocks of data written by said central processing unit, which are to be written to said peripheral device in accordance with a command from said central processing unit;
a control unit, connected between said channelling means and said peripheral device, said control unit further comprising a buffer memory means for temporarily storing the block of data which is to be written to said peripheral device a recording means for recording a block number corresponding to a most recently written block of data in said peripheral device from said buffer memory means, and said control unit comprising a control means for issuing a command necessary to write said block of data stored in the buffer memory means to said peripheral device, including the block number associated with the block of data stored in said buffer memory means;
and
means for deleting the block of said which has been previously written to said peripheral device from said backup memory means.

2 more elements

A method of backing up a buffered peripheral system which is connected to a central processing unit, wherein said buffered peripheral system includes primary and back-up control units and a backup memory means to store blocks of data to be written to a peripheral device, said primary and back-up control units having a buffer memory means for temporarily storing a block of data, each of said first and second control units comprising a control means for issuing a command necessary to write the block of data stored in said buffer memory means to said peripheral device, including a block number associated with the block of data stored in said buffer memory means and a recording area for recording the block number corresponding to a most recently written block of data to said peripheral device from said buffer memory means, said buffer memory means being used for storing a copy of the contents of said backup memory means, said method comprising the steps of:

(a) detecting a fault in said buffer memory in said primary control unit;
(b) determining whether the content of said recording means can be read out from said buffer memory in said primary control unit;
and
(c) carrying out one of first and second processings, the first processing being carried out when the contents of said recording means can be read out, said first processing including the sub-steps of:
(i) reading out the block number corresponding to a most recently written block of data to said peripheral device;
(ii) changing said primary control unit that is in fault over to said back-up control unit;
(iii) writing blocks of data which are stored in said backup memory means and which correspond to subsequent block numbers following the block number recorded in said recording means, to said peripheral device through said back-up control unit;
and
(iv) deleting the blocks of data corresponding to the block number recorded in said recording means and block numbers preceding said block number recorded in said recording means, from said backup memory means;
(d) said second processing being carried out when the content of said recording means cannot be read out, said second processing including the sub-steps of:
(i) changing said primary control unit that is in fault over to said back-up control unit;
(ii) determining the block number which corresponds to a most recently written block of data to said peripheral device;
(iii) writing the blocks of data which are stored in said backup memory means and which correspond to subsequent block numbers following the block number recorded in said recording means, to said peripheral device through said back-up control unit;
and
(iv) deleting the blocks of data corresponding to the block number recorded in said recording means and block numbers preceding said block number recorded in said recording means, from said backup memory means.

12 more elements

Dependencies are inferred from the claim text.

Buffered peripheral system and method for backing up and retrieving data to and from backup memory device

Life of this patent

Buffered peripheral system and method for backing up and retrieving data to and from backup memory device

Life of this patent

Abstract

Claims5