Latency-aware live migration for multitenant database platforms
View Patent ↗Methods and systems for database migration from a multitenant database include taking a snapshot of an original database to be migrated with a hot backup process, such that the database is still capable of answering queries during the hot backup process; maintaining a query log of all queries to the tenant database after the hot backup process begins; initializing a new database at a target server using the snapshot; replaying the query log synchronize the new database with the original database; and answering new queries with the new database and not the original database.
1. A method for migration from a multitenant database, comprising:
taking a snapshot of an original database to be migrated with a hot backup process, such that the database is still capable of answering queries during the hot backup process;
selecting a database migration method that does not generate a service level agreement (SLA) violation and otherwise selecting a method that generates the fewest SLA violations during the database migration;
applying a proportional-integral-derivative (PID) controller to determine a speed of migration based on system performance, wherein the PID controller has a proportional path, an integral path and a derivative path, each path is scaled by coefficients K p , K i , and K d respectively, wherein an output at time t with error e(t) is given by:
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maintaining a query log of all queries to the tenant database after the hot backup process begins;
initializing a new database at a target server using the snapshot;
replaying the query log to synchronize the new database with the original database; and
answering new queries with the new database and not the original database.
2. The method of claim 1 , further comprising computing a target level of performance based on meeting service level agreement (SLA) guarantees.
3. The method of claim 2 , further comprising moderating a speed of the hot backup process based on current and historic system performance.
4. The method of claim 3 , wherein moderating the speed comprises comparing current and historic system performance to the computed target level of performance to whether to increase or decrease speed in accordance with a respective shortfall or surplus relative to the target level of performance.
5. The method of claim 3 , wherein moderating the speed comprises allocating resources to the hot backup process to optimize a backup speed while maintaining SLA guarantees.
6. The method of claim 5 , wherein the resources comprise a storage input/output rate and a network bandwidth.
7. The method of claim 3 , wherein moderating the speed comprises using a proportional-integral-derivative controller to adaptively respond to changes in an amount of slack resources.
8. The method of claim 1 , wherein the amount of slack resources is determined by comparing the measured transaction latency to a target transaction latency that represents an optimal balance between speed of the backup process and transactions for other tenants.
9. A multitenant database system, comprising:
code to select a database migration method that does not generate a service level agreement (SLA) violation and otherwise select a method that generates the fewest SLA violations during the database migration;
a proportional-integral-derivative (PID) controller coupled to the database system to determine a speed of migration based on system performance, wherein the PID controller has a proportional path, an integral path and a derivative path, each path is scaled by coefficients K p , K i , and K d respectively, wherein an output at time t with error e(t) is given by:
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and
a multitenant database configured to take a snapshot of an original tenant database to be migrated with a hot backup process, such that the original tenant database is still capable of answering queries during the hot backup process, to maintain a query log of all queries to the original tenant database using a processor after the hot backup process begins, to initialize a migrated tenant database using a received snapshot, and to replay a received query log to synchronize the migrated tenant database with an original tenant database.