Adaptive failure survivability in a storage system using save time and data transfer after power loss

• US 9,141,505 B1
• Filed: 09/27/2012
• Issued: 09/22/2015
• Est. Priority Date: 09/27/2012
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Crow, Preston F., McClure, Steven T., Natarajan, Preethi
• Primary Examiner(s): Chu, Gabriel
• Assistant Examiner(s): CONTINO, PAUL F
• Application Number:
  US13/628,259
• Time in Patent Office: 1,090 Days
• Field of Search: 714/22, 714/24, 711/162
• US Class Current: 1/1
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/30 Monitoring
• 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 11/3037 where the computing system component is a memory, e.g. virtual memory, cache accessing, addressing or allocating within memory systems or architectures G06F12/00; checking stores for correct operation G11C29/00
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16
• 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 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 2201/81 Threshold
• CPC Class Codes: G06F 2212/1032 Reliability improvement, data loss prevention, degraded operation etc
• CPC Class Codes: G06F 2212/21 Employing a record carrier using a specific recording technology
• CPC Class Codes: G06F 2212/281 Single cache
• CPC Class Codes: G06F 2212/313 In storage device
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/068 Hybrid storage device

Abstract

Maintaining failure survivability in a storage system includes determining a save time corresponding to an amount of time needed to transfer system data from volatile memory to non-volatile memory, determining a threshold corresponding to time for batteries to run while transferring data from volatile memory to non-volatile memory after a power loss, and providing an indication in response to the save time being greater than the threshold. The system may include a plurality of directors and the save time and the threshold may be determined for each of the directors. Determining a threshold may include determining an amount of battery time provided by battery power following power loss and multiplying the amount of battery time by a factor less than one, such as 0.8.

Claims

1. A method of maintaining failure survivability in a storage system, comprising:

for each of a plurality of units of the storage system, performing the following;

(a) determining a transfer time to transfer data from volatile memory to non-volatile memory of the unit of the storage system;

(b) determining a storage time to store the data in the non-volatile memory;

(c) determining whether the data requires encryption, and where the determination indicates that the data requires encryption, determining an encryption time to encrypt the data prior to storage in the non-voltage memory;

(d) determining a save time corresponding to an amount of time needed to move the data from volatile memory to non-volatile memory, wherein the save time includes a sum of the transfer time, the storage time and the encryption time; and

(e) determining a threshold corresponding to time for batteries to run while moving the data from the volatile memory to the non-volatile memory after a power loss;

providing an indication in response to the save time being greater than the threshold for at least one of the units of the storage system;

comparing the save times determined for the plurality of units to determine a first unit having a longer save time and a second unit having a shorter save time;

modifying a storage plan for the moving of the data to reconfigure storage of data among the first and second units based on the comparing of the save times, wherein the modifying the storage plan includes setting data that would have been stored according to the storage plan to the first unit having the longer save time to be stored instead on the second unit having the shorter save time; and

performing additional reconfiguration in response to the save time being greater than the threshold, wherein the additional reconfiguration includes changing data set to be stored in a first portion of non-volatile memory to be set to be stored in a second, different, portion of the volatile memory.

2. A method, according to claim 1, wherein the plurality of units of the storage system includes a plurality of directors and wherein the save time and the threshold are determined for each of the directors.

3. A method, according to claim 2, wherein the indication is provided in response to a save time for at least one of the directors being greater than the threshold for the at least one of the directors.

4. A method, according to claim 1, wherein determining a threshold includes determining an amount of battery time provided by battery power following power loss and adjusting the amount.

5. A method, according to claim 4, wherein the amount is adjusted by subtracting a predetermined value.

6. A method, according to claim 1, further comprising:

destaging cache data from volatile memory to disks of a storage device in response to the save time being greater than the threshold.

7. A non-transitory computer-readable medium storing software that maintains failure survivability in a storage system, the software comprising:

executable code that, for each of a plurality of units of the storage system, performs the following;

(a) determines a transfer time to transfer data from volatile memory to non-volatile memory of the unit of the storage system;

(b) determines a storage time to store the data in the non-volatile memory;

(c) determines whether the data requires encryption, and where the determination indicates that the data requires encryption, determining an encryption time to encrypt the data prior to storage in the non-voltage memory;

(d) determines a save time corresponding to an amount of time needed to move the data from volatile memory to non-volatile memory, wherein the save time includes a sum of the transfer time, the storage time and the encryption time; and

(e) determines a threshold corresponding to time for batteries to run while moving the data from the volatile memory to the non-volatile memory after a power loss;

executable cede that provides an indication in response to the save time being greater than the threshold for at least one of the units of the storage system;

executable code that compares the save times determined for the plurality of units to determine a first unit having a longer save time and a second unit having a shorter save time;

executable code that modifies a storage plan for the moving of the data to reconfigure storage of data among the first and second units based on the comparing of the save times, wherein the executable code that modifies the storage plan includes executable code that sets data that would have been stored according to the storage plan to the first unit having the longer save time to be stored instead on the second unit having the shorter save time; and

executable code that performs additional reconfiguration in response to the save time being greater than the threshold, wherein the additional reconfiguration includes changing data set to be stored in a first portion of non-volatile memory to be set to be stored in a second, different, portion of the volatile memory.

8. The non-transitory computer-readable medium according to claim 7, wherein the plurality of units of the storage system includes a plurality of directors and wherein the save time and the threshold are determined for each of the directors.

9. The non-transitory computer-readable medium according to claim 8, wherein the indication is provided in response to a save time for at least one of the directors being greater than the threshold for the at least one of the directors.

10. The non-transitory computer-readable medium according to claim 7, wherein executable code that determines a threshold determines an amount of battery time provided by battery power following power loss and adjusting the amount.

11. The non-transitory computer-readable medium according to claim 10, wherein the amount is adjusted by subtracting a predetermined value.

12. The non-transitory computer-readable medium according to claim 7, further comprising:

executable code that destages cache data from volatile memory to disks of a storage device in response to the save time being greater than the threshold.