Storage systems implementing offset erasure code stripes
地域：
NY
NY Armonk
摘要
A computer-implemented method, according to one embodiment, includes: selecting strips from each storage unit for a given erasure code stripe such that the given erasure code stripe includes at most one strip from a high failure rate region of the respective storage unit, where each of the storage units include high and low failure rate regions. The selected strips are organized such that a number of each strip in the given erasure code stripe is offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions. The organized selected strips are further mapped to form the given erasure code stripe such that the high failure rate regions on each storage unit are mapped to one or more sequentially numbered strips, and the low failure rate regions are mapped to additional sequentially numbered strips.
說(shuō)明書
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The present invention relates to data storage, and more specifically, this invention relates to implementing offset (e.g., skewed) erasure code stripes across optical disks.
Data are stored on a variety of different storage medium types. For instance, data storage systems include many different storage units which include hard disk drives (HDDs), optical disks, solid state drives (SSDs), etc. It follows that in some data storage systems, optical disks are transported from physical storage locations to a disk drive in order to write data to and/or read data from the optical disks.
While utilizing optical disks to store data is beneficial for many reasons, optical disks are not invulnerable to reliability issues. For instance, most optical disks do not have an integrated protective casing and are therefore susceptible to data transfer problems due to scratches, fingerprints, and other environmental problems that result from the optical disks being used. Some specific locations on optical disks may even have systematically higher failure probability than other locations thereon, perhaps due to contamination or contact by the storage system mechanics with the surface of the disk.
Erasure codes are implemented in an attempt to remedy these data access failures when they occur. However, a standard erasure code will place strips from the same location in each optical disk in the same erasure code stripe. Thus, erasure code stripes which include strips from high failure rate regions on the storage units for each of those strips have an abnormally high probability of experiencing multiple coincident failures. This in turn will overwhelm the protective capability of the erasure code in these conventional implementations.
權(quán)利要求
What is claimed is:1. An erasure code protected storage system, comprising:a processor; and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor, the logic being configured to, for erasure code stripes in storage units: select, by the processor, strips from each storage unit for a given erasure code stripe such that the given erasure code stripe includes at most one strip from a high failure rate region of the respective storage unit, wherein each of the storage units include high failure rate regions and low failure rate regions; organize, by the processor, the selected strips such that a number of each strip in the given erasure code stripe is offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions; and map, by the processor, the organized selected strips to form the given erasure code stripe, wherein the high failure rate regions on each storage unit are mapped to one or more sequentially numbered strips, wherein the low failure rate regions are mapped to additional sequentially numbered strips. 2. The erasure code protected storage system of claim 1 , wherein organizing the selected strips includes:dividing the strips into N sequentially numbered sets of strips, where N is a number of devices in an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 3. The erasure code protected storage system of claim 1 , wherein the erasure code stripes are multi-dimensional, wherein organizing the selected strips includes:dividing the strips into M sequentially numbered sets of strips, where M is a number of devices on dimension of an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 4. The erasure code protected storage system of claim 1 , wherein the high failure rate regions on each storage unit are mapped to one or more contiguously numbered strips, wherein selecting strips from each storage unit for the given erasure code stripe includes:selecting strips that are each offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions. 5. The erasure code protected storage system of claim 1 , wherein the storage units are optical disks. 6. The erasure code protected storage system of claim 5 , wherein the high failure rate regions are located near an outer diameter of each of the optical disks. 7. The erasure code protected storage system of claim 5 , wherein the high failure rate regions are located in areas of high contamination and/or damage on a surface of at least some of the optical disks. 8. The erasure code protected storage system of claim 1 , comprising:one or more hard disk drives. 9. The erasure code protected storage system of claim 1 , comprising:one or more solid state drives. 10. A computer-implemented method for enabling erasure code protection for storage units, comprising, for erasure code stripes in the storage units:selecting strips from each storage unit for a given erasure code stripe such that the given erasure code stripe includes at most one strip from a high failure rate region of the respective storage unit, wherein each of the storage units include high failure rate regions and low failure rate regions; organizing the selected strips such that a number of each strip in the given erasure code stripe is offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions; and mapping the organized selected strips to form the given erasure code stripe, wherein the high failure rate regions on each storage unit are mapped to one or more sequentially numbered strips, wherein the low failure rate regions are mapped to additional sequentially numbered strips. 11. The computer-implemented method of claim 10 , wherein organizing the selected strips includes:dividing the strips into N sequentially numbered sets of strips, where N is a number of devices in an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 12. The computer-implemented method of claim 10 , wherein the erasure code stripes are multi-dimensional, wherein organizing the selected strips includes:dividing the strips into M sequentially numbered sets of strips, where M is a number of devices on dimension of an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 13. The computer-implemented method of claim 10 , wherein the high failure rate regions on each storage unit are mapped to one or more contiguously numbered strips, wherein selecting strips from each storage unit for the given erasure code stripe includes:selecting strips that are each offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions. 14. The computer-implemented method of claim 10 , wherein the storage units are optical disks. 15. The computer-implemented method of claim 14 , wherein the high failure rate regions are located near an outer diameter of each of the optical disks. 16. The computer-implemented method of claim 14 , wherein the high failure rate regions are located in areas of high contamination and/or damage on a surface of at least some of the optical disks. 17. A computer program product for enabling erasure code protection for storage units, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a processor to cause the processor to, for erasure code stripes in the storage units:select, by the processor, strips from each storage unit for a given erasure code stripe such that the given erasure code stripe includes at most one strip from a high failure rate region of the respective storage unit, wherein each of the storage units include high failure rate regions and low failure rate regions; organize, by the processor, the selected strips such that a number of each strip in the given erasure code stripe is offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions; and map, by the processor, the organized selected strips to form the given erasure code stripe, wherein the high failure rate regions on each storage unit are mapped to one or more sequentially numbered strips, wherein the low failure rate regions are mapped to additional sequentially numbered strips. 18. The computer program product of claim 17 , wherein organizing the selected strips includes:dividing the strips into N sequentially numbered sets of strips, where N is a number of devices in an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 19. The computer program product of claim 17 , wherein the erasure code stripes are multi-dimensional, wherein organizing the selected strips includes:dividing the strips into M sequentially numbered sets of strips, where M is a number of devices on dimension of an erasure code group, wherein the strips in the given erasure code stripe are each selected from different sets. 20. The computer program product of claim 17 , wherein the high failure rate regions on each storage unit are mapped to one or more contiguously numbered strips, wherein selecting strips from each storage unit for the given erasure code stripe includes:selecting strips that are each offset from the remaining strips by an amount that is greater than a total number of strips in the high failure rate regions. 21. The computer program product of claim 17 , wherein the storage units are optical disks. 22. The computer program product of claim 21 , wherein the high failure rate regions are located near an outer diameter of each of the optical disks. 23. The computer program product of claim 21 , wherein the high failure rate regions are located in areas of high contamination and/or damage on a surface of at least some of the optical disks.
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