Predictive point-in-time copy for storage systems

• US 9,857,996 B2
• Filed: 06/13/2013
• Issued: 01/02/2018
• Est. Priority Date: 12/18/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wilkinson, John P.
• Primary Examiner(s): Rones, Charles
• Assistant Examiner(s): Chang, Tian-Pong
• Application Number:
  US14/650,855
• Publication Number:
  US 20150309745A1
• Time in Patent Office: 1,664 Days
• CPC Class Codes: G06F 11/1446 Point-in-time backing up or restoration of persistent data
• CPC Class Codes: G06F 11/2056 by mirroring
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0683 Plurality of storage devices

Abstract

Method and system are provided for predictive point-in-time copy for storage systems. The method may include: recording a frequency of writes to an area of a storage volume; and prioritizing areas for having point-in-time copies carried out based on the write frequency to an area, wherein areas in the storage volume having a high write frequency are prioritized before areas with a lower write frequency. An area may be of a coarser granularity than a region tracked for the point-in-time copy. The method may include: recording the frequency of writes to an area in a given period; and prioritizing areas by their frequency of writes in the given period immediately prior to the point-in-time copy.

Claims

1. A method for predictive point-in-time copying for storage systems to reduce an amount of data used during a point-in-time copy, comprising:

recording a frequency of writes to one or more areas of a storage volume, wherein the frequency of writes to the one or more areas are recorded as a rolling count of writes for each area in a given period of time;

prioritising, immediately prior to a point-in-time copy for a region, each area for having the point-in-time copy of the region carried out based on the write frequency to each area during the given period of time,

wherein areas in the storage volume having a high write frequency during the given period of time are prioritised before areas with a lower write frequency during the given period of time,

wherein an area is of a greater granularity than the region tracked for the point-in-time copy, and

wherein an area is of a greater granularity than the region tracked when the area has a size of 2 times n, wherein n is a size of the region tracked; and

automatically increasing a point-in-time copy rate during periods of fewer writes from host applications.

2. The method as claimed in claim 1, further comprising:

running a point-in-time copy when a write rate is below an average write rate.

3. The method as claimed in claim 1, wherein prioritising each area includes:

determining a time of a previous point-in-time copy for the storage volume; and

weighting recordings of writes which occur nearest to the time of the previous point-in-time copy.

4. The method as claimed in claim 3, further comprising:

defining time segments from the time of the previous point-in-time copy and weighting writes according to the segment in which they take place.

5. The method as claimed in claim 1, further comprising:

initially synchronising a point-in-time copy for a volume and only copying newly-written regions of the volume in subsequent point-in-time copies; and

prioritising partial writes to an area.

6. The method as claimed in claim 1, wherein recording a frequency of writes to an area of a storage volume includes:

intercepting input and outputs of a host server.

7. A system for predictive point-in-time copying for storage systems to reduce an amount of data used during a point-in-time copy, comprising:

a memory; and

a processor, wherein the processor is configured to perform operations comprising;

recording a frequency of writes to one or more areas of a storage volume, wherein the frequency of writes to the areas are recorded as a rolling count of writes for each area in a given period of time;

prioritising, immediately prior to a point-in-time copy for a region, each area for having the point-in-time copy of the region carried out based on the write frequency to each area during the given period of time,

wherein areas in the storage volume having a high write frequency during the given period of time are prioritised before areas with a lower write frequency during the given period of time,

wherein an area is of a greater granularity than the region tracked for the point-in-time copy, and

wherein an area is of a greater granularity than the region tracked when the area has a size of 2 times n, wherein n is a size of the region tracked; and

automatically increasing a point-in-time copy rate during periods of fewer writes from host applications.

8. The system as claimed in claim 7, further comprising:

running a point-in-time copy when a write rate is below an average write rate.

9. The system as claimed in claim 7, further comprising:

determining a time of a previous point-in-time copy for the volume; and

weighting recordings of writes which occur nearest to the time of the previous point-in-time copy.

10. The system as claimed in claim 9, further comprising:

defining time segments from the time of the previous point-in-time copy and weighting writes according to the segment in which they take place.

11. The system as claimed in claim 7, further comprising:

initially synchronising a point-in-time copy for a volume and only copying newly-written regions of the volume in subsequent point-in-time copies; and

prioritising partial writes to an area.

12. The system as claimed in claim 7, further comprising:

copying data from the first point-in-time copy that is deleted to a second point-in-time copy that requires the data, wherein the first point-in-time copy was written before the second point-in-time copy.

13. A computer program product for predictive point-in-time copying for storage systems to reduce an amount of data used during a point-in-time copy, the computer program product comprising:

a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

recording a frequency of writes to one or more areas of a storage volume, wherein the frequency of writes to the areas are recorded as a rolling count of writes for each area in a given period of time;

prioritising, immediately prior to a point-in-time copy for a region, each area for having the point-in-time copy of the region carried out based on the write frequency to each area during the given period of time,

wherein areas in the storage volume having a high write frequency during the given period of time are prioritised before areas with a lower write frequency during the given period of time,

wherein an area is of a greater granularity than the region tracked for the point-in-time copy, and

wherein an area is of a greater granularity than the region tracked when the area has a size of 2 times n, wherein n is a size of the region tracked;

copying data from a first point-in-time copy of a region to a first area in the storage volume having a high write frequency; and

automatically increasing a point-in-time copy rate during periods of fewer writes from host applications.