MANAGING CONCURRENT FILE SYSTEM ACCESSES BY MULTIPLE SERVERS USING LOCKS
First Claim
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1. A method of managing accesses to a resource of a shared file system that is stored in a data storage unit (DSU), comprising:
- reading a lock associated with the resource to obtain a current state of the lock;
determining that the lock is available based on the current state;
transmitting a request to the DSU to perform an atomic update to the lock comprising a first operation to confirm that the current state of the lock has not changed since the reading and a second operation to acquire the lock, wherein no other operation can be performed on the lock between the first operation and second operation; and
acquiring access to the resource upon receiving confirmation of successful completion of the atomic update, whereby no exclusive reservation of the DSU is required to acquire the lock.
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Abstract
Atomic test and set (ATS) operations are carried out to perform lock operations that allow a node to acquire or release a lock to a resource of a shared file system that is stored in a data storage unit (DSU) and update its liveness information. Each ATS operation includes the step of comparing contents accessed and read through the shared file system and contents stored at a particular logical block number of the DSU. If the two contents match, updates to the contents of the lock or the liveness information are permitted.
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Citations
20 Claims
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1. A method of managing accesses to a resource of a shared file system that is stored in a data storage unit (DSU), comprising:
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reading a lock associated with the resource to obtain a current state of the lock; determining that the lock is available based on the current state; transmitting a request to the DSU to perform an atomic update to the lock comprising a first operation to confirm that the current state of the lock has not changed since the reading and a second operation to acquire the lock, wherein no other operation can be performed on the lock between the first operation and second operation; and acquiring access to the resource upon receiving confirmation of successful completion of the atomic update, whereby no exclusive reservation of the DSU is required to acquire the lock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A non-transitory computer-readable storage medium including instructions for managing accesses to a resource of a shared file system that is stored in a data storage unit (DSU), that when executed by a computer processor, perform the steps of:
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reading a lock associated with the resource to obtain a current state of the lock; determining that the lock is available based on the current state; transmitting a request to the DSU to perform an atomic update to the lock comprising a first operation to confirm that the current state of the lock has not changed since the reading and a second operation to acquire the lock, wherein no other operation can be performed on the lock between the first operation and second operation; and acquiring access to the resource upon receiving confirmation of successful completion of the atomic update, whereby no exclusive reservation of the DSU is required to acquire the lock. - View Dependent Claims (10, 11, 12)
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13. The non-transitory computer-readable storage medium, wherein the lock comprises an owner ID field and a lease field specifying a period of time for possessing the lock.
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14. A method of updating a heartbeat region associated with a node and stored in a data storage unit (DSU), comprising:
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identifying a heartbeat region associated with a node, wherein the heartbeat region stores liveness information associated with the node; generating updated liveness information associated with the node; and performing an atomic update operation on the heartbeat region to store the updated liveness information in the heartbeat region, wherein at least one other resource of the shared file system is accessible while the atomic update operation is being performed. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification