Tape emulating disk based storage system and method with automatically resized emulated tape capacity
View Patent ↗A data protection and storage system includes an array of disk drives for data storage. Data is received for storage on the disk drive via an interface that is configured to emulate a tape drive interface. A virtual tape data structure is created and stored on the disk drives. The allocated capacity of the virtual tape is dynamically and transparently alterable in response to data storage demand within the virtual tape.
1. A data storage system comprising:
one or more disk drives;
an interface configured to emulate a tape drive and to receive data for storage on said one or more disk drives using tape format data storage commands and tape storage data formats; and
a storage controller configured to pre-allocate a portion of the storage space on said one or more disk drives to a tape storage volume that receives data via said interface,
wherein said storage controller is further configured to automatically change the amount of storage space pre-allocated to said tape storage volume in response to tape format data storage commands received via said interface, and
wherein the pre-allocated portion comprises both free portions of the pre-allocated portion of the storage space and used portions of the pre-allocated portion of the storage space
wherein said storage controller is configured to decrease the amount of storage space pre-allocated to said tape storage volume if a write command to overwrite a logical block address corresponding to a tape record number below a threshold is received.
2. The data storage system of claim 1 , wherein said one or more disk drives and said storage controller are mounted within a common housing.
3. The data storage system of claim 1 , wherein at least one of said one or more disk drives and said storage controller are mounted in separate housings.
4. The data storage system of claim 1 , wherein said interface communicates in an iSCSI or Fibre Channel format.
5. The data storage system of claim 1 , wherein said storage controller is configured to increase the amount of storage space pre-allocated to said tape storage volume only if said increase does not place said pre-allocated storage space above a pre-determined maximum.
6. The data storage system of claim 5 , wherein said storage controller is configured to generate a warning if said increase would place said pre-allocated storage space above said pre-determined maximum.
7. A data storage device comprising:
at least one hard disk drive;
a tape drive emulator;
at least one emulated magnetic tape having a pre-defined apparent storage capacity provided by at least some of the storage capacity of said hard disk drive; and
means for automatically changing the pre-defined apparent storage capacity of said emulated magnetic tape in response to write commands received by said tape drive emulator,
wherein pre-defined apparent storage capacity comprises both free portions of the pre-defined apparent storage capacity and used portions of the pre-defined apparent storage capacity
wherein a storage controller is configured to decrease the amount of pre-defined apparent storage capacity to said emulated magnetic tape if a write command to overwrite a logical block address corresponding to a tape record number below a threshold is received.
8. The data storage device of claim 7 , wherein said means for automatically changing the pre-defined apparent storage capacity of said emulated magnetic tape comprises a stored value indicating an end of data sector and an early warning sector, and a storage controller configured to compare said end of data sector and early warning sector.
9. The data storage device of claim 7 , wherein said emulated magnetic tape is defined by entries in a stored tape header file that includes values for a beginning of media sector and an end of media sector.
10. The data storage device of claim 9 , wherein said tape header file additionally defines a value for an early warning sector.
11. The data storage system of claim 1 , wherein the storage controller is further configured to pre-allocate a second portion of the storage space on said one or more disk drives to a second tape storage volume that receives data via said interface, and wherein at least a portion of the pre-allocated first portion and at least a portion of the pre-allocated second portion are located on a single disk drive.