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US 7,254,736 B2Granted
Systems and method providing input/output fencing in shared storage environments
AssigneeVeritas Operating Corporation
InventorsRonald S. Karr, John A. Colgrove, Oleg Kiselev
Life of this patent
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Abstract
Systems and methods for I/O fencing in a shared storage environment are provided. Prior to initiating an I/O request, when feasible, the current time from a local timer is compared to the current state of an interval obtained for the target device. As a result, a device reset occurring while the interval is viable does not arbitrarily end a multiphase I/O operation. However, a device reset occurring once the lease has expired results in a delay or termination of the multiphase I/O operation. As a result, multiphase I/O operations from initiating hosts that have lost contact with the shared storage environment are not allowed to corrupt the shared storage devices.
Claims38
A method of Input/Output (I/O) fencing comprising:
- establishing an end time of a time interval after which access is not allowed to a target device by a requesting device;
- initiating a multiphase write operation to the target device, wherein the multiphase write operation includes a first phase wherein the requesting device sends a write request to the target device, a second phase wherein the target device sends a response to the requesting device indicating that the target device is ready to write, a third phase wherein the requesting device sends data to the target device, and a fourth phase wherein the target device sends a response to the requesting device indicating that the data was written, wherein initiating the multiphase write operation comprises the requesting device initiating the first phase of the multiphase write operation;
- obtaining a time value prior to the requesting device initiating the third phase of the multiphase write operation;
- and
- interfering with the third phase of the multiphase write operation in response to determining that the time value is greater than the end time.
2 more elements
An Input/Output (I/O) fencing system comprising:
- a reliable clock for establishing an end time of a time interval after which access is not allowed to a target device by a requesting device;
- means for initiating a multiphase write operation to the target device, wherein the multiphase write operation includes a first phase wherein the requesting device sends a write request to the target device, a second phase wherein the target device sends a response to the requesting device indicating that the target device is ready to write, a third phase wherein the requesting device sends data to the target device, and a fourth phase wherein the target device sends a response to the requesting device indicating that the data was written, wherein initiating the multiphase write operation comprises initiating the first phase of the multiphase write operation;
- means for obtaining a time value prior to initiating the third phase of the multiphase write operation;
- and
- means for interfering with the third phase of the multiphase write operation in response to determining that the time value is greater than the end time.
2 more elements
A method of Input/Output (I/O) fencing comprising;
- establishing an end time of a time interval after which access is not allowed to a target device by a requesting device;
- performing a login operation to enable initiation of a multiphase write operation to the target device, wherein the multiphase write operation includes a first phase wherein the requesting device sends a write request to the target device, a second phase wherein the target device sends a response to the requesting device indicating that the target device is ready to write, a third phase wherein the requesting device sends data to the target device, and a fourth phase wherein the target device sends a response to the requesting device indicating that the data was written;
- initiating the multiphase write operation to the target device, wherein initiating the multiphase write operation comprises initiating the first phase of the multiphase write operation;
- obtaining a time value after initiating the first phase of the multiphase write operation;
- performing a re-login operation in response to determining that the time value is less than the end time;
- and
- initiating the third phase of the multiphase write operation after performing the re-login operation.
4 more elements
An Input/Output (I/O) fencing system comprising;
- a reliable clock for establishing an end time of a time interval after which access is not allowed to a target device by a requesting device;
- means for performing a login operation to enable initiation of a multiphase write operation to the target device, wherein the multiphase write operation includes a first phase wherein the requesting device sends a write request to the target device, a second phase wherein the target device sends a response to the requesting device indicating that the target device is ready to write, a third phase wherein the requesting device sends data to the target device, and a fourth phase wherein the target device sends a response to the requesting device indicating that the data was written;
- means for initiating the multiphase write operation to the target device, wherein initiating the multiphase write operation comprises initiating the first phase of the multiphase write operation;
- means for obtaining a time value after initiating the first phase of the multiphase write operation;
- means for performing a re-login operation in response to determining that the time value is less than the end time;
- and
- means for initiating the third phase of the multiphase write operation after performing the re-login operation.
4 more elements
Dependencies are inferred from the claim text.