US 9,852,154 B2 · Methods for transferring reserves when moving virtual machines across systems

Abstract

According to one embodiment, a method includes receiving device information from a source system; building a virtual device on a host system based at least in part on the received device information; at least one of: transferring a reserve of a device stored on a storage device to a target system; and receiving results of transferring the reserve to the target system; determining if the reserve is held by the target system; recording the reserve if the reserve is held by the target system; and sending a notification that the reserve is not held by the target system if the reserve is not held by the target system. Other methods are also described according to various embodiments.

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Drawings

Claims17

Dependent claims

A method, comprising:

receiving device information about a first device, the device information being received by a target system from a source system;
building a virtual device on the target system that is equivalent to a virtual device on the source system based at least in part on the received device information;
setting a flag byte in a command input for a new reserve holder specifying whether a push command or a pull command will transfer a reserve of the first device, wherein the new reserve holder is the target system;
initiating, using the target system, transfer of the reserve of the first device from the source system to the target system by sending an indication to the source system that the virtual device build is complete in response to completion of the virtual device build, wherein the reserve of the first device is transferred using a synchronous push command at the source system, the synchronous push command forcing a response that indicates whether the push command was successful or unsuccessful, wherein the transferring the reserve to the target system comprises:
retrieving a path group identifier (PGID) for each of:
an invoker system, a reserve holder system, and the command input for the new reserve holder;
determining whether the PGID of the reserve holder system is the same as the PGID of the invoker system;
and
in response to a determination that the PGID of the reserve holder system is the same as the PGID of the invoker system:
setting the PGID of the reserve holder system to the PGID of the command input for the new reserve holder;
and
sending a notification to the invoker system that transferring the reserve was successful;
receiving results from the source system at the target system of transferring the reserve of the first device to the target system indicating a successful transfer in response to a determination that the synchronous push command was successful and indicating an unsuccessful transfer in response to a determination that the synchronous push command was unsuccessful;
recording, in response to receiving the results, the reserve in response to a determination that a status check on the reserve indicates that the reserve is held by the target system;
and
sending a notification that the reserve is not held by the target system in response to a determination that the status check on the reserve indicates that the reserve is not held by the target system.

13 more elements

A method, comprising:

issuing, from a target system to a source system, a reserve command for a first device;
receiving device information about the first device in response to the reserve command, the device information being received by the target system from the source system;
building a virtual device on the target system that is equivalent to a virtual device on the source system based at least in part on the received device information;
setting a flag byte in a command input for a current reserve holder specifying that a pull command will transfer a reserve of the first device, wherein the current reserve holder is the source system;
transferring, using the target system, the reserve of the first device from the source system to the target system using a synchronous pull command, the synchronous pull command forcing a response regarding whether the synchronous pull command was successful or unsuccessful, wherein the transferring the reserve to the target system comprises:
retrieving a path group identifier (PGID) for each of:
the target system, the source system, and the command input for the current reserve holder;
determining whether the PGID of the command input for the current reserve holder is the same as the PGID of the source system;
in response to a determination that the PGID of the command input for the current reserve holder is the same as the PGID of the source system:
setting the PGID of the command input for the current reserve holder to the PGID of the target system;
and
sending a notification to the target system that transferring the reserve was successful;
receiving results from the source system at the target system of transferring the reserve of the first device to the target system indicating that the reserve is held by the target system in response to a determination that the synchronous pull command was successful and indicating that the reserve is not held by the target system in response to a determination that the synchronous pull command was unsuccessful;
recording, in response to receiving the results, the reserve in response to a determination that a status check on the reserve indicates that the reserve is held by the target system after a successful synchronous pull command of the reserve from the source system to the target system;
and
sending a notification that the reserve is not held by the target system in response to a determination that a status check on the reserve indicates that the reserve is not held by the target system after an unsuccessful synchronous pull command of the reserve from the source system to the target system.

13 more elements

A method, comprising:

receiving device information about a first device, the device information being received by a target system from a source system;
building a virtual device on the target system that is equivalent to a virtual device on the source system based at least in part on the received device information;
transferring a reserve of the first device from the source system to the target system using a synchronous pull command initiated by the target system, the pull command forcing a response regarding whether the pull command was successful or unsuccessful, wherein the transferring of the reserve comprises:
retrieving a path group identifier (PGID) for each of:
the target system, the source system, and a command input for a current reserve holder;
setting a flag byte in the command input specifying that the synchronous pull command will transfer the reserve of the first device;
determining whether the PGID of the command input for the current reserve holder is the same as the PGID of the source system;
in response to a determination that the PGID of the command input for the current reserve holder is the same as the PGID of the source system:
setting the PGID of the command input for the current reserve holder to the PGID of the target system;
and
sending a notification to the target system that transferring the reserve was successful;
in response to a determination that the PGID of the command input is not the same as the PGID of the source system, delaying for an amount of time;
and
in response to a determination that the PGID of the command input for the current reserve holder is not the same as the PGID of the source system after the amount of time, sending a notification to the target system that the transferring of the reserve was not successful;
receiving results, at the target system, of the transferring of the reserve of the first device to the target system indicating a successful transfer in response to a determination that the synchronous pull command was successful and indicating an unsuccessful transfer in response to a determination that the synchronous pull command was unsuccessful;
recording, in response to receiving the results, the reserve in response to a determination that a status check on the reserve indicates that the reserve is held by the target system;
and
sending a notification that the reserve is not held by the target system in response to a determination that the status check on the reserve indicates that the reserve is not held by the target system.

15 more elements

Dependencies are inferred from the claim text.

Description7,629 words

Summary416 words

#The present invention relates to data storage systems, and more particularly, this invention relates to methods and systems for maintaining data integrity when moving virtual machines across systems.

#In many storage systems, there are instances in which a device in a storage unit is held such that a specific host system has exclusive access to the device. This is typically accomplished by issuing a command from a host system to a control unit which controls the device. The exclusive access to the device is maintained by the host system until the host releases this exclusive access. In general, this command may be held in order to maintain consistency of data on this device when changes are occurring, e.g., another server is not able to access the data on this held device while the host system makes changes to the data on the device. In addition to holding this device, there are conditions in which the host system may transfer this exclusive access to this device to another (host) system. In typical storage systems, this can be done by the target host system querying the current state of the device that is being held to verify that the source host is actually holding the access to this device. After this point, the target host system or source host system issues an unconditional command to take or reassign the access to this device unconditionally. By unconditionally, what is meant is that this command takes control of or reassigns the access to this device regardless of any other ownership or control by another entity, e.g., this unconditional command takes the access to this device no matter which entity is holding the device.

#In one embodiment, a method includes receiving device information from a source system, building a virtual device on a host system based at least in part on the received device information, transferring a reserve of a device stored on a storage device to a target system and/or receiving results of transferring the reserve to the target system, determining if the reserve is held by the target system, recording the reserve if the reserve is held by the target system, and sending a notification that the reserve is not held by the target system if the reserve is not held by the target system.

Brief description of the drawings10 figures

#FIG. 1 illustrates a system architecture, in accordance with one embodiment.

#FIG. 2 shows a representative hardware environment that may be associated with the systems of FIG. 1, in accordance with one embodiment.

#FIG. 3 shows a flowchart of a reserve transfer, according to one embodiment.

Detailed description7,061 words

#The following description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations.

#Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc.

#It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified.

Facts

Application

13/483,731Filed 30 May 2012 · continuation

Priority

10 Nov 2010

Published

US 2012/0117196 A127 Sep 2012

Granted

26 Dec 2017

Term ends

24 Jul 2031

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 256 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification2 codes

G06F 16/188
File system types: virtual file systems
G06F
Computing and data processing

Timeline

10 Nov 2010Priority claimedParent application 12/943,874
30 May 2012Application filedUS 13/483,731
27 Sep 2012PublishedUS 2012/0117196 A1
12 Oct 2016Assigned to International Business Machines Corporationassignment of assignor's interest
26 Dec 2017GrantedUS 9,852,154 B2
12 Oct 2026TodayWithin its term
24 Jul 2031Term endsEstimated, includes 256 days of adjustment

Methods for transferring reserves when moving virtual machines across systems

Life of this patent

Methods for transferring reserves when moving virtual machines across systems

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims17

Description7,629 words

Drawings

Classification2 codes

Life of this patent

Description7,629 words