SCSI-to-IP Cache Storage Device and Method

• US 20080010411A1
• Filed: 09/18/2007
• Published: 01/10/2008
• Est. Priority Date: 08/15/2002
• Status: Active Grant

• Current Assignee: State of Rhode Island and Providence Plantations
• Original Assignee: Rhode Island Board of education (STATE OF RHODE ISLAND)
• Inventors: Yang, Qing, He, Xubin
• Granted Patent: US 7,953,926 B2
• Time in Patent Office: Days
• US Class Current: 711/122
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A SCSI-to-IP cache storage system interconnects a host computing device or a storage unit to a switched packet network. The cache storage system includes a SCSI interface (40) that facilitates system communications with a host computing device or the storage unit, and a Ethernet interface (42) that allows the system to receive data from and send data to the Internet. The cache storage system further comprises a processing unit (44) that includes a processor (46), a memory (48) and a log disk (52) configured as a sequential access device. The log disk (52) caches data along with the memory (48) resident in the processing unit (44), wherein the log disk (52) and the memory (48) are configured as a two-level hierarchical cache.

Claims

1-5. -5. (canceled)

6. A processor-readable medium containing instructions that, when executed by a processor, cause the processor to implement a method for storing data in a cache storage system, the method comprising:

receiving data at a processing unit, wherein the data is sent from a device selected from the group consisting of;

a host computing device via a small computer system interface (SCSI) and a first remote cache storage system communicably coupled to a switched packet network via a network interface;

storing the received data in a buffer;

transferring data from the buffer to a log disk when the amount of data in the buffer exceeds a threshold value or when the log disk is idle, wherein the transferred data is the least recently used data in the buffer; and

in the event that the amount of data in the log disk exceeds a threshold, transferring, via the network interface, a portion of the data from the log disk to a second remote cache storage system communicably coupled to the switched packet network.

7. The medium of claim 6, wherein the second remote cache storage system is operating at the lowest processing load relative to other remote cache storage systems communicably coupled to the switched packet network.

8. The medium of claim 6, wherein the method further comprises:

receiving a write request prior to said receiving data.

9. A processor-readable medium containing instructions that, when executed by a processor, cause the processor to implement a method for storing data in a cache storage system, the method comprising:

receiving a read request at a processing unit, wherein the read request is sent from a requesting device, the requesting device being selected from the group consisting of;

a host computing device sending the read request via a SCSI and a first remote cache storage system communicably coupled to a switched packet network and sending the read request via a network interface;

retrieving data associated with the read request from a unit selected from the group consisting of;

a buffer in the processing unit, a log disk coupled to the processing unit, a storage device coupled to the processing unit, and a second remote cache storage system communicably coupled to the switched packet network;

transferring the retrieved data to the requesting device;

transferring data from the buffer to the log disk when the amount of data in the buffer exceeds a threshold value or when the log disk is idle, wherein the transferred data is the least recently used data in the buffer; and

in the event that the amount of data in the log disk exceeds the threshold value, transferring, via the network interface, data from the log disk to a third remote cache storage system communicably coupled to the switched packet network.

10. The medium of claim 9, wherein the third remote cache storage system is operating at the lowest processing load relative to other remote cache storage systems communicably coupled to the switched packet network.