On-demand initialization of memory locations as they are requested command

• US 5,943,689 A
• Filed: 03/31/1997
• Issued: 08/24/1999
• Est. Priority Date: 03/31/1997
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Tamer, Philip
• Primary Examiner(s): Cabeca, John W.
• Assistant Examiner(s): Lee, Felix B.
• Application Number:
  US08/831,503
• Time in Patent Office: 876 Days
• Field of Search: 711/166, 711/206, 711/4
• US Class Current: 711/166
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

An on demand method of initializing a data storage medium, the method including the steps of: specifying a region of the data storage medium that is to be initialized in preparation for storing data in that region; setting up a table for keeping track of which portions of the region have been initialized; in response to receiving a request for accessing a specified location within the region, checking the table to determine whether the location to which access is being requested had been previously initialized; if the table indicates that the specified location has not been previously initialized, initializing that specified location within the data storage medium; and updating the table to indicate that the specified location within the data storage medium has been initialized.

Claims

1. An on-demand method of initializing a data storage medium, said method comprising:

specifying a region of the data storage medium that is to be initialized in preparation for storing application data in that region;

storing a predetermined string of bits to be used for initializing the region of the data storage medium;

setting up a table for keeping track of which portions of the region have been initialized;

in response to receiving each read request that identifies a specified location within the region,

(a) checking the table to determine whether the specified location had been previously initialized;

(b) if the table indicates that the specified location has not been previously initialized, initializing that specified location within the data storage medium by writing said predetermined string of bits to the specified location; and

(c) in addition to initializing the specified location, updating the table to indicate that the specified location within the data storage medium has been initialized.

2. The method of claim 1 further comprising:

(d) after initializing the specified location, performing a read operation in fulfillment of the read request.

3. The method of claim 2 further comprising:

(e) if the table indicates that the specified location has been previously initialized, performing the read operation without performing any further initialization of the specified location.

4. The method of claim 1 wherein said predetermined string is all zeros.

5. A method implemented within a data storage system to which a host processor is connected for initializing on demand a storage medium within the data storage system, said method comprising:

receiving an initialization command from the host processor;

in response to receiving the initialization command, setting up a table containing a plurality of records for a corresponding plurality of blocks in the storage medium, each of said plurality of records storing an entry that equals a first value;

storing an initialization value to be used for initializing the data storage medium;

receiving read commands from the host processor, said read commands identifying a region of the storage medium to which a read access is being requested, said identified region encompassing at least one block among said plurality of blocks; and

in response to receiving each read command,

(a) determining whether the entry in a record in the table corresponding to said one block equals the first value;

(b) if the entry in the corresponding record equals the first value, writing said initialization value into said one block in the data storage medium;

(c) in addition to writing said initialization value into said one block, setting the entry in the corresponding record for that block to a second value; and

(d) performing the access requested by the access command.

6. The method of claim 5 wherein the initialization command is a sequence of multiple commands.

7. The method of claim 5 wherein the initialization command also passes said initialization value to the data storage system.

8. A data storage system that provides data storage for a host processor, the data storage system comprising:

a data storage medium; and

a controller programmed to carry out the following steps;

in response to receiving an on-demand initialization command specifying a region of the data storage medium that is to be initialized in preparation for the host processor storing application data in that region, setting up a table for keeping track of which portions of the region have been initialized;

storing a predetermined string of bits to be used for initializing the region of the data storage medium; and

in response to receiving each of a plurality of read requests from the host processor, each read request for reading a corresponding specified location within the region,

(a) checking the table to determine whether the corresponding specified location has been previously initialized;

(b) if the table indicates that the corresponding specified location has not been previously initialized, initializing that corresponding specified location within the data storage medium by writing said predetermined string of bits to the corresponding specified location; and

(c) in addition to initializing that specified location, updating the table to indicate that the corresponding specified location within the data storage medium has been initialized.