Method and system for preventing data loss within disk-array pairs supporting mirrored logical units
First Claim
Patent Images
1. A reliable computing and data-storage system comprising:
- a first host computer linked to a second host computer by a first communications medium;
a first mass-storage device, linked to the first host computer by a second communications medium;
a second mass-storage device, linked to the second host computer by a third communications medium;
a fourth communications medium directly linking the first mass-storage device to the second mass-storage device for transmission of sequenced data written to a dominant logical unit within the first mass-storage device to the second mass-storage device for writing to a remote-mirror logical unit;
a first link that directly links the first mass-storage device to the first communications medium;
a second link that directly links the second mass-storage device to the first communications medium;
controller logic within controllers of the first and second mass-storage devices, the controller logic within at least one controller detecting a failure of the fourth communications medium, the controller logic within both controllers cooperating to retransmit any lost data from the first mass-storage device to the second mass-storage device by way of the first and second links and the first communications medium.
2 Assignments
0 Petitions
Accused Products
Abstract
An additional communications link between two mass-storage devices containing LUNs of a mirrored-LUN pair, as well as incorporation of a fail-safe mass-storage-device-implemented retry protocol to facilitate non-drastic recovery from communications link failures within the controllers of the two mass-storage devices, prevents build-up of WRITE requests in cache and subsequent data loss due to multiple communications-link and host computer failures. The combination of the additional link and the retry protocol together ameliorates a deficiency in current LUN-mirroring implementations that often leads to data loss and inconsistent and unrecoverable databases.
35 Citations
12 Claims
-
1. A reliable computing and data-storage system comprising:
-
a first host computer linked to a second host computer by a first communications medium; a first mass-storage device, linked to the first host computer by a second communications medium; a second mass-storage device, linked to the second host computer by a third communications medium; a fourth communications medium directly linking the first mass-storage device to the second mass-storage device for transmission of sequenced data written to a dominant logical unit within the first mass-storage device to the second mass-storage device for writing to a remote-mirror logical unit; a first link that directly links the first mass-storage device to the first communications medium; a second link that directly links the second mass-storage device to the first communications medium; controller logic within controllers of the first and second mass-storage devices, the controller logic within at least one controller detecting a failure of the fourth communications medium, the controller logic within both controllers cooperating to retransmit any lost data from the first mass-storage device to the second mass-storage device by way of the first and second links and the first communications medium. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A reliable computing and data-storage system comprising:
-
a first host computer linked to a second host computer by a first communications medium; a first mass-storage device, linked to the first host computer by a second communications medium; a second mass-storage device, linked to the second host computer by a third communications medium; a fourth communications medium directly linking the first mass-storage device to the second mass-storage device for transmission of sequenced data written to a dominant logical unit within the first mass-storage device to the second mass-storage device for writing to a remote-mirror logical unit; a first link that directly links the first mass-storage device to the first communications medium; a second link that directly links the second mass-storage device to the first communications medium; and controller logic within controllers of the first and second mass-storage devices that detect a failure of the fourth communications medium and transmit any lost, and all subsequent, data for writing to the remote-mirror logical unit from the first mass-storage device to the second mass-storage device by way of the first and second links and the first communications medium. - View Dependent Claims (7, 8, 9, 10, 11)
-
-
12. A method for increasing the reliability of a computing and data-storage having a first host computer linked to a second host computer by a first communications medium, a first mass-storage device, linked to the first host computer by a second communications medium, a second mass-storage device, linked to the second host computer by a third communications medium, and a fourth communications medium directly linking the first mass-storage device to the second mass-storage device for transmission of sequenced data written to a dominant logical unit within the first mass-storage device to the second mass-storage device for writing to a remote-mirror logical unit, the method comprising:
-
providing a first link that directly links the first mass-storage device to the first communications medium; providing a second link that directly links the second mass-storage device to the first communications medium; detecting, by a controller within the second mass-storage device, a failure to receive sequenced data from the first mass-storage device by the second mass-storage device and requesting retransmission, by the controller within the second mass-storage device from the first mass-storage device, of the data that was not received by the second mass-storage device; and detecting a failure of the fourth communications medium by a controller within the first mass-storage device and transmitting any lost, and all subsequent, data for writing to the remote-mirror logical unit from the first mass-storage device to the second mass-storage device by way of the first and second links and the first communications medium.
-
Specification