Method and system to maintain data consistency over an internet small computer system interface (iSCSI) network
First Claim
1. A method to transfer data writes from a primary site to a secondary site, for disaster recovery purposes, said method comprising:
- inserting a PiT marker beginning a PiT frame to be transferred;
logging data writes in a primary journal, wherein said data writes are ordered in the point-in-time (PiT) frame;
inserting a PiT marker indicating end of said PiT frame to be transferred;
iteratively obtaining data writes saved in said PiT frame;
generating, for each data write to be transferred, a small computer system interface (SCSI) command;
transferring said generated SCSI command to said secondary site using the iSCSI protocol; and
saving a data write encapsulated in the SCSI command in a secondary journal.
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Accused Products
Abstract
A method and system is disclosed to maintain data consistency over an internet small computer system interface (iSCSI) network, for disaster recovery and remote data replication purposes. Data consistency and replication is maintained between primary and secondary sites geographically distant from each other. According to the method, a primary journal volume logs all changes (data writes) made to a primary volume, transmits the changes based on a preconfigured policy to a secondary journal volume, and thereafter merges the changes stored in the secondary journal volume with a secondary volume. Changes in the journal volumes are ordered in point-in-time (PiT) frames and transmitted using a vendor specific SCSI command utilizing the iSCSI protocol.
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Citations
69 Claims
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1. A method to transfer data writes from a primary site to a secondary site, for disaster recovery purposes, said method comprising:
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inserting a PiT marker beginning a PiT frame to be transferred;
logging data writes in a primary journal, wherein said data writes are ordered in the point-in-time (PiT) frame;
inserting a PiT marker indicating end of said PiT frame to be transferred;
iteratively obtaining data writes saved in said PiT frame;
generating, for each data write to be transferred, a small computer system interface (SCSI) command;
transferring said generated SCSI command to said secondary site using the iSCSI protocol; and
saving a data write encapsulated in the SCSI command in a secondary journal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer program product comprising a computer-readable medium with instructions to enable a computer to implement a process for transferring data writes from a primary site to a secondary site, for disaster recovery purposes, said medium comprising:
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computer readable program code working in conjunction with a computer to insert a PiT marker beginning a PiT frame to be transferred;
computer readable program code working in conjunction with a computer to log data writes in a primary journal, wherein said data writes are ordered in the point-in-time (PiT) frame;
computer readable program code working in conjunction with a computer to insert a PiT marker indicating end of said PiT frame to be transferred;
computer readable program code working in conjunction with a computer to iteratively obtain data writes saved in said PiT frame;
computer readable program code working in conjunction with a computer to generate, for each data write to be transferred, a small computer system interface (SCSI) command;
computer readable program code working in conjunction with a computer to transfer said generated SCSI command to said secondary site using the ISCSI protocol; and
computer readable program code working in conjunction with a computer to save a data write encapsulated in the SCSI command in a secondary journal. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method to maintain data consistency over an internet small computer system interface (iSCSI) network, said method comprising:
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copying content of a primary volume to a secondary volume;
receiving data writes from at least one host;
saving, simultaneously, said received data writes in a primary volume and in a primary journal, wherein said saved data writes in said primary journal are ordered in point-in-time (PiT) frames; and
initiating, according to a predefined policy, a transfer of at least one PiT frame from said primary journal to a secondary journal, said transfer comprising;
inserting a PiT marker in said primary journal, said PiT marker indicating end of said PiT frame;
iteratively obtaining data writes saved in said PiT frame;
generating, for each data write to be transferred, a small computer system interface (SCSI) command;
transferring said generated SCSI command to a secondary site via the iSCSI protocol; and
saving a data write encapsulated in said SCSI command in a secondary journal. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A computer program product comprising a computer-readable medium with instructions to enable a computer to implement a method maintaining data consistency over an internet small computer system interface (iSCSI) network, said medium comprising:
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computer readable program code working in conjunction with said computer to copy content of a primary volume to a secondary volume;
computer readable program code working in conjunction with said computer to receive data writes from at least one host;
computer readable program code working in conjunction with said computer to save, simultaneously, said received data writes in a primary volume and in a primary journal, wherein said saved data writes in said primary journal are ordered in point-in-time (PiT) frames; and
computer readable program code working in conjunction with said computer to initiate, according to a predefined policy, a transfer of at least one PiT frame from said primary journal to a secondary journal, said transfer comprising;
inserting a PiT marker in said primary journal, said PiT marker indicating end of said PiT frame;
iteratively obtaining data writes saved in said PiT frame;
generating, for each data write to be transferred, a small computer system interface (SCSI) command;
transferring said generated SCSI command to a secondary site via the iSCSI protocol; and
saving a data write encapsulated in said SCSI command in a secondary journal. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A system for maintaining data consistency over an internet small computer system interface (iSCSI) network, the system comprises at least:
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a network interface communicating with a plurality of hosts through a network;
a data transfer arbiter (DTA) handling data writes transfer between a plurality of storage devices and the plurality of hosts;
wherein said DTA further controls the process of maintaining data consistency;
a device manager (DM) interfacing with the plurality of storage devices; and
a journal transcriber transferring data writes from a primary site to a secondary site. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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Specification