REDISTRIBUTING DATA ACROSS DRIVES OF A STORAGE ARRAY BASED ON DRIVE HEALTH METRICS

• US 20200133772A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Dalmatov, Nickolay Alexandrovich, Shraifel, Alexander
• Granted Patent: US 10,733,051 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/008 Reliability or availability analysis
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/3058 Monitoring arrangements for monitoring environmental properties or parameters of the computing system or of the computing system component, e.g. monitoring of power, currents, temperature, humidity, position, vibrations thermal management in cooling arrangements of a computing system G06F1/206
• CPC Class Codes: G06F 11/3447 Performance evaluation by modeling
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0649 Lifecycle management
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

Techniques are presented for maintaining data distributed across a plurality of storage drives (drives) in a robust manner. A method includes (a) collecting physical state information from each drive of the plurality of drives, (b) generating a predicted failure probability of each drive based on the collected physical state information from that drive, the predicted failure probability indicating a likelihood that that drive will fail within a predetermined period of time, and (c) rearranging a distribution of data across the plurality of drives to minimize a probability of DU/DL. Systems, apparatuses, and computer program products for performing similar methods are also provided.

Claims

1. A method of maintaining data distributed across a plurality of storage drives (drives) in a robust manner, the method comprising:

collecting physical state information from each drive of the plurality of drives;

generating a predicted failure probability of each drive based on the collected physical state information from that drive, the predicted failure probability indicating a likelihood that that drive will fail within a predetermined period of time; and

rearranging a distribution of data across the plurality of drives to minimize a probability of data unavailability/data loss (DU/DL).

2. The method of claim 1 wherein rearranging the distribution of data includes remapping an address space of a logical disk (LUN) so that areas of drives that have lower predicted failure probabilities are configured to store user data and areas of drives that have higher predicted failure probabilities are configured to map to areas of the address space that do not store user data.

3. The method of claim 2,

wherein the plurality of drives are arranged in a fixed RAID configuration having a set of stripes, each stripe going across all drives of the plurality of drives;

and

remapping the address space includes mapping the address space of the LUN to exclude areas of stripes that are on drives that have higher predicted failure probabilities.

4. The method of claim 3 wherein mapping the address space of the LUN to exclude areas of stripes that are on drives that have higher failure probabilities includes moving data already stored on the areas of stripes that are on drives that have higher failure probabilities to areas of stripes that are on drives that have lower failure probabilities.

5. The method of claim 3 wherein mapping the address space of the LUN to exclude areas of stripes that are on drives that have higher failure probabilities includes writing new user data to areas of stripes that are on drives that have lower failure probabilities instead of to areas of stripes that are on drives that have higher failure probabilities.

6. The method of claim 2,

wherein the plurality of drives are arranged in a Mapped RAID configuration having a set of stripes, each stripe going across fewer than all of the plurality of drives;

and

remapping the address space includes mapping the address space of the LUN to exclude areas of stripes that are on drives that have higher predicted failure probabilities.

7. The method of claim 1,

wherein the plurality of drives are arranged in a Mapped RAID configuration having a set of stripes, each stripe going across fewer than all of the plurality of drives;

and

wherein rearranging the distribution of data includes rearranging the set of stripes so that areas of stripes that are initially on drives that have higher predicted failure probabilities are moved to drives that have lower predicted failure probabilities.

8. The method of claim 1 wherein rearranging the distribution of data includes:

determining a current probability of DU/DL;

searching a space of different distributions of data across the plurality of drives for a distribution of data that has a lowest probability of DU/DL; and

in response to determining that the current probability of DU/DL exceeds the lowest probability of DU/DL by at least a predetermined threshold, moving data in accordance with the distribution of data that has the lowest probability of DU/DL.

9. The method of claim 1 wherein rearranging the distribution of data includes:

determining a current probability of DU/DL;

searching a space of different distributions of data across the plurality of drives for an alternate distribution of data that satisfies the following conditions;

the alternate distribution has a lower probability of DU/DL such that the current probability of DU/DL exceeds the lower probability of DU/DL by at least a predetermined threshold and

the alternate distribution has a skew below a maximum permitted skew value; and

moving data in accordance with the alternate distribution of data.

10. A computer program product comprising a non-transitory computer-readable storage medium storing a set of instructions, which, when performed by a computing device, cause the computing device to maintain data distributed across a plurality of storage drives (drives) in a robust manner by:

collecting physical state information from each drive of the plurality of drives;

generating a predicted failure probability of each drive based on the collected physical state information from that drive, the predicted failure probability indicating a likelihood that that drive will fail within a predetermined period of time; and

rearranging a distribution of data across the plurality of drives to minimize a probability of data unavailability/data loss (DU/DL).

11. The computer program product of claim 10 wherein rearranging the distribution of data includes remapping an address space of a logical disk (LUN) so that areas of drives that have lower predicted failure probabilities are configured to store user data and areas of drives that have higher predicted failure probabilities are configured to map to areas of the address space that do not store user data.

12. The computer program product of claim 10,

wherein the plurality of drives are arranged in a Mapped RAID configuration having a set of stripes, each stripe going across fewer than all of the plurality of drives;

and

wherein rearranging the distribution of data includes rearranging the set of stripes so that areas of stripes that are initially on drives that have higher predicted failure probabilities are moved to drives that have lower predicted failure probabilities.

13. A data storage system (DSS) comprising:

a plurality of storage drives (drives);

a set of persistent storage device that provide a pool of persistent storage; and

a computing device communicatively-connected to the set of persistent storage devices, the computing device being configured to maintain data distributed across the plurality of drives in a robust manner by;

collecting physical state information from each drive of the plurality of drives;

generating a predicted failure probability of each drive based on the collected physical state information from that drive, the predicted failure probability indicating a likelihood that that drive will fail within a predetermined period of time; and

rearranging a distribution of data across the plurality of drives to minimize a probability of data unavailability/data loss (DU/DL).

14. The DSS of claim 13 wherein rearranging the distribution of data includes remapping an address space of a logical disk (LUN) so that areas of drives that have lower predicted failure probabilities are configured to store user data and areas of drives that have higher predicted failure probabilities are configured to map to areas of the address space that do not store user data.

15. The DSS of claim 13,

wherein the plurality of drives are arranged in a Mapped RAID configuration having a set of stripes, each stripe going across fewer than all of the plurality of drives;

and

wherein rearranging the distribution of data includes rearranging the set of stripes so that areas of stripes that are initially on drives that have higher predicted failure probabilities are moved to drives that have lower predicted failure probabilities.