# US 8,572,343 B2 · Synchronous extent migration protocol for paired storage

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- Number: US 8,572,343 B2
- Document ID: US8572343B2
- Status: Granted
- Kind: B2
- Application number: 13/523,643
- Filed: 2012-06-14
- Published: 2012-10-11
- Granted: 2013-10-29
- Earliest claimed: 2010-12-16
- Assignees: International Business Machines Corporation
- Applicants: Paul A. Jennas, II; Larry Juarez; David Montgomery; Todd C. Sorenson
- Inventors: Paul A. Jennas, II; Larry Juarez; David Montgomery; Todd C. Sorenson
- Web page: https://patentgrep.com/patent/US8572343B2

## CPC

- G06F 11/2097: {maintaining the standby controller/processing unit updated (initialisation or re-synchronisation thereof G06F11/1658 and subgroups)}
- G06F 3/061: {Improving I/O performance}
- G06F 3/0647: {Migration mechanisms}
- G06F 3/0685: {Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Extent migration is provided in a data storage environment configured for synchronous replication between a primary and secondary pair of storage entities, each having tiered storage devices. In one embodiment, by way of example only, a migration instruction is sent, by the primary storage entity, to the secondary storage entity, the migration instruction including a time delta approximately equal to a time of an intended migration at the primary storage entity adjusted for a transmission time such that the primary and secondary storage entities conduct the extent migration at approximately a same time.

## Claims

### Claim 1

In a data storage environment configured for synchronous replication between a primary and secondary pair of storage entities, each having tiered storage devices, a method for extent migration by a processor device, comprising:
sending, by the primary storage entity, a migration instruction to the secondary storage entity, the migration instruction including a time delta approximately equal to a time of an intended migration at the primary storage entity adjusted for a transmission time such that the primary and secondary storage entities conduct the extent migration at approximately a same time.

### Claim 2 (depends on 1)

The method of claim 1, further including, by at least a storage activity factor, identifying an extent as a candidate for the extent migration.

### Claim 3 (depends on 1)

The method of claim 1, further including configuring the migration instruction with at least one of an extent identifier field, a time delta field, in which the time delta is incorporated, and a destination tier number field.

### Claim 4 (depends on 3)

The method of claim 3, further including performing at least one calculation to obtain at least one of an extent identifier value, the time delta, and a destination tier number for insertion into the migration instruction.

### Claim 5 (depends on 1)

The method of claim 1, further including, upon receipt of the migration instruction by the secondary storage entity, queueing an extent to be migrated pursuant to the extent migration at a migration time calculated as a current time plus the time delta.

### Claim 6 (depends on 5)

The method of claim 5, further including migrating the extent at the migration time.