Method and apparatus to move page between tiers
AssigneeHitachi, Ltd.
InventorShinichi Hayashi
Life of this patent
Estimating the term…
Abstract
The thin provisioning storage system maintains migration history between the first and the second group which the unallocated pages of virtual volume would be allocated from, and updates on writes against storage areas of virtual volume having migration history. Before the storage controller determines to migrate data allocated in the first group to the second group, the storage controller checks the migration history and if the data stored in the first group has been previously migrated from the second group and is still maintained in the second group, the storage controller would change the allocation between the virtual volume and the first group to the second group for the data subject to migration and not perform the data migration.
Claims16
A storage system comprising:
- a storage controller including a processor and a memory;
- and a plurality of storage devices, wherein the storage controller groups the plurality of storage devices into a first group and a second group and provides a virtual volume to a server, the storage controller allocating storage areas from the first and second group to the virtual volume in response to a write request, and wherein before the storage controller determines to migrate data stored in the first group to the second group, the storage controller checks a migration history maintained in the memory and if the data stored in the first group has been previously migrated from the second group and is still maintained in the second group, the storage controller would change the allocation between the virtual volume and the first group to the second group for the data subject to migration and not perform the data migration.
A method for managing a storage system coupled to a server via a network, the method comprising:
- receiving a write command from the server, and if a page of a virtual volume subject to the write command is unallocated, allocating storage area from a plurality of storage devices to the page of the virtual volume;
- before determining to move data from a first page of the virtual volume allocated to a second group to a first group, checking a migration history from the first group to the second group and data updates against the first page of the virtual volume, changing an allocation between the virtual volume and the second group to the first group and not transferring data subject to move depending on the checked results;
- wherein a storage controller changes the allocation between the virtual volume and the second group to the first group if the migration history stores that the first page of the virtual volume was previously moved from the first group to the second group and that the data was not updated against the first page of the virtual volume.
Dependencies are inferred from the claim text.