Method and apparatus for optimizing the performance of a storage system

• US 8,756,387 B2
• Filed: 03/05/2010
• Issued: 06/17/2014
• Est. Priority Date: 03/05/2010
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Frost, Holloway H., Scheel, Daniel E.
• Primary Examiner(s): Bansal, Gurtej
• Application Number:
  US12/718,705
• Publication Number:
  US 20110219170A1
• Time in Patent Office: 1,565 Days
• Field of Search: 711/100, 711/111, 711/118, 711/162, 711/202
• US Class Current: 711/162
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 12/02 Addressing or allocation; Relocation program address sequencing G06F9/00; arrangements for selecting an address in a digital store G11C8/00
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0638 Combination of memories, e.g. ROM and RAM such as to permit replacement or supplementing of words in one module by words in another module address formation of the next microinstruction G06F9/26; masking faults in memories by using spares or by reconfiguring G11C29/70
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/154 Networked environment
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/261 Storage comprising a plurality of storage devices
• CPC Class Codes: G06F 2212/70 Details relating to dynamic memory management
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• 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 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/068 Hybrid storage device

Abstract

Methods and apparatuses for optimizing the performance of a storage system comprise a FLASH storage system, a hard drive storage system, and a storage controller. The storage controller is adapted to receive READ and WRITE requests from an external host, and is coupled to the FLASH storage system and the hard drive storage system. The storage controller receives a WRITE request from an external host containing data and an address, forwards the received WRITE request to the FLASH storage system and associates the address provided in the WRITE request with a selected alternative address, and provides an alternative WRITE request, including the selected alternative address and the data received in the WRITE request, to the hard drive storage system, wherein the alternative address is selected to promote sequential WRITE operations within the hard drive storage system.

Claims

1. A storage system for processing READ and WRITE requests from an external host, the storage system comprising:

(A) a FLASH storage system configured as a primary storage space for the storage system;

(B) a backup hard drive storage system configured to back up data stored on the FLASH storage system, the backup hard drive storage system having a storage space that is an integer factor less than the storage space of the FLASH storage system and divided into a plurality of blocks; and

(C) a storage controller configured to receive READ and WRITE requests from an external host, the storage controller being coupled to the FLASH storage system and the backup hard drive storage system such that the storage controller can issue READ and WRITE requests to both the FLASH storage system and the backup hard drive storage system, wherein the storage controller is configured to;

(i) receive a WRITE request from an external host, the WRITE request containing data and an address corresponding to a location where such data is to be stored and;

(a) forward the received WRITE request to the FLASH storage system, the FLASH storage system configured to perform a WRITE operation based on the data and address from the WRITE request;

(b) associate the address provided in the WRITE request with a selected alternative address, and provide an alternative WRITE request to the backup hard drive storage system wherein the alternative WRITE request includes the selected alternative address and the data received in the WRITE request, the backup hard drive storage configured to perform a WRITE operation based on the data and the selected alternative address from the alternative WRITE request, wherein the alternative address is selected to achieve substantially sequential WRITE operations on the plurality of blocks within the backup hard drive storage system; and

(ii) receive a READ request from an external host, the READ request containing an address corresponding to a location from which data is to be read and;

(a) forward the received READ request to the FLASH storage system, the FLASH storage system configured to perform a READ operation based on the address from the READ request and to provide data resulting from the READ operation to the storage controller;

(b) return the data received from the FLASH storage system to the external host in the absence of a READ error from the FLASH storage system;

or

(c) issue an alternative READ request to the backup hard drive storage system, the alternative READ request containing an address corresponding to an alternative address associated by the storage controller with the address received from the external host in the READ request and returning the data received from the backup hard drive storage system to the external host in the event of a READ error from the FLASH storage system; and

(iii) identify one or more alternative addresses to be compacted in the backup hard drive storage system that are out of sequence for a next alternative WRITE operation and contain stale or invalid data, and;

(a) issue one or more READ requests to the FLASH storage system, the one or more READ requests containing one or more addresses corresponding to the one or more alternative addresses to be compacted;

(b) if data received from the FLASH storage system in response to the one or more READ requests is valid data, issue one or more WRITE requests to the backup hard drive storage system, the one or more WRITE requests containing the data received from the FLASH storage system and the one or more alternative addresses to be compacted; and

(c) if data received from the FLASH storage system in response to the one or more READ requests results in faulty or erroneous data, issue one or more READ requests to the backup hard drive storage system containing one or more alternative addresses corresponding to the one or more addresses that resulted in the faulty or erroneous data, issue one or more WRITE requests to the backup hard drive storage system containing data received from the backup hard drive storage system and the one or more alternative addresses to be compacted, and issue one or more WRITE requests to FLASH storage system containing the data received from the backup hard drive storage system and the one or more addresses that resulted in the in faulty or erroneous data.

2. The storage system of claim 1 wherein the FLASH storage system comprises SLC FLASH memory.

3. The storage system of claim 1 wherein the controller is further configured to:

determine whether the address provided with the WRITE request was already associated with data stored in the backup hard drive storage system at the time that the WRITE request was received and,

if the determination indicates that the provided address was already associated with data stored in the backup hard drive storage system, provide an indication that the data stored is no longer valid data.

4. The storage system of claim 1 wherein the backup hard drive storage system is configured to store data across the disc array in a striped manner.

5. The storage system of claim 1 wherein the storage controller comprises a programmed microprocessor within a server.

6. The storage system of claim 1 wherein the storage controller is configured to issue a WRITE request to the FLASH storage system in the event of a READ error from the FLASH storage system, the WRITE request including data obtained from the backup hard drive storage system.

7. The storage system of claim 1 wherein the controller is further configured to:

determine whether the address provided with the WRITE request was already associated with an alternate address in the backup hard drive storage system,

if the determination indicates that the address provided with the WRITE request was already associated with an alternate address in the backup hard drive storage system, provide an indication that the alternate address is no longer valid and associate the address provided with the WRITE request with a next sequential alternate address in backup hard drive storage system.

8. The storage system of claim 1 wherein the controller is further configured to:

determine whether the address provided with the WRITE request was already associated with an alternate address in the backup hard drive storage system,

if the determination indicates that the address provided with the WRITE request was already associated with an alternate address in the backup hard drive storage system, then;

provide an indication that the data stored at the alternate address is no longer valid,

write the data provided with the WRITE request to a next sequential alternate address in the backup hard drive storage system and associate the address provided with the WRITE request with the next sequential alternate address in backup hard drive storage system, and

move data that was stored at the next sequential alternate address in the backup hard drive storage system to another alternate address in the backup hard drive storage system.

9. The storage system of claim 1 wherein achieving substantially sequential WRITE operations on the plurality of blocks within the backup hard drive storage system comprises skipping over sequential blocks that already have valid data stored therein and storing the data included in the alternative WRITE request in a sequential block that does not already have valid data stored therein.

10. The storage system of claim 1 wherein the storage controller is configured to provide an indication of overall storage space to the external host, and wherein the indication of overall storage space identifies a storage space that is one or more factors less than the storage space provided by the backup hard drive storage system.