System for distributing volumes to an HSM system front end

• US 5,974,515 A
• Filed: 04/08/1997
• Issued: 10/26/1999
• Est. Priority Date: 04/08/1997
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Bachmat, Hagit, Bachmat, Eitan
• Primary Examiner(s): Chan, Eddie P.
• Assistant Examiner(s): Encarnacion, Yamir
• Application Number:
  US08/835,772
• Time in Patent Office: 931 Days
• Field of Search: 341/81, 711/153, 711/114, 711/170, 711/148, 711/173, 711/4, 711/112, 711/201, 395/182.04, 395/182.05, 395/828, 710/8, 714/6, 714/7
• US Class Current: 711/170
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems

Abstract

A system for distributing logical volumes to an HSM system front end by ordering an array of logical volumes so that each volume that is likely to conflict with another volume is significantly separated from that other volume. Ordering is done iteratively, beginning with the disk type, and then iterating through the logical volume level, next through a target level (the physical disk), then SCSI level, then the disk adapter level, then system level until all the disks in all the disk adapters in the HSM system have been ordered. As each iteration occurs, units in a source array from the level being operated on are ordered so that those close to each other are moved apart, within the space available, in the destination array according to a procedure that establishes a gap between them that is based on an approximate ratio of the number of units in the source array to the number of spaces available in the destination array. When the volumes have been distributed, the present invention allocates the distributed volumes to ports on the host computers sharing the HSM system and also optimizes distribution of RAID subgroups, if possible.

Claims

1. A computer-implemented method for distributing volume units to host computers sharing a multi-volume disk system having a plurality of levels of organization comprising the steps of:

placing a first level into at least one source array having a plurality of elements;

ordering a first source array into a destination array for a next level, the destination array having a number of elements equal to or greater than the sum of the number of elements in all source arrays being ordered into the destination array;

calculating a gap for spacing empty elements apart between the elements of the destination array according to the following procedures;

space="preserve" listing-type="equation">gap=trunc(ratio×

(i+1)+0.5)-trunc(ratio×

i+0.5).

where trunc instructs the computer system to round the result down, i is an index to the selected element in the destination array, and ratio is calculated by dividing the number of empty elements left in the destination array by the total number of elements in the destination array.

spacing the elements in the destination array said gap for spacing empty elements apart, whereby the destination array becomes the source array for the next level until all levels have been ordered.

2. The method of claim 1, wherein the step of spacing the elements in the destination array further includes the step of updating.

3. A computer-implemented system for distributing volume units to host computers sharing a multi-volume disk system having a plurality of levels of organization:

a processor having memory coupled to it for storing arrays;

a distribution program executing in the processor for ordering arrays whereby the distribution program places a first level into at least one source array having a plurality of elements, orders a first source array into a destination array for a next level, the destination array having a number of elements equal to or greater than the sum of the number of elements in all source arrays being ordered into the destination array;

said distribution program calculating the number of empty spaces according to the following procedure;

space="preserve" listing-type="equation">gap=trunc(ratio×

(i+1)+0.5)-trunc(ratio×

i+0.5),

where trunc instructs the computer system to round the result down, i is an index to the selected element in the destination array, and ratio is calculated by dividing the number of empty elements left in the destination array by the total number of elements in the destination array;

said distribution program spacing the elements in the destination array said gap spacing the number of empty elements apart, whereby the destination array becomes the source array for the next level until all levels have been ordered.

4. The system of claim 3, wherein said distribution program spacing the elements in the destination array includes updating.