Managing mapped raid extents in data storage systems
A technique for use in managing mapped RAID extents is disclosed. A neighborhood matrix denoting a distribution of neighboring physical storage portions across the N physical storage devices of the pool is created and initialized. A disk extent consumed array denoting a disk consumption metric is created and initialized. Disks in an extent pool are analyzed to identify a least consumed disk in the extent pool and a disk extent is allocated from the identified disk. The allocated disk extent is configured as a first disk extent for a first RAID extent. The neighborhood matrix and disk extent consumed array are updated appropriately. All the disks in the extent pool are analyzed to identify a valid disk extent that will result in the lowest variance value in the neighborhood matrix. The identified valid disk extent is allocated and the neighborhood matrix and disk extent consumed array are again updated.
1. A method for use in managing mapped RAID extents in data storage systems, the method comprising:
creating and initializing a neighborhood matrix denoting a distribution of neighboring physical storage portions across the N physical storage devices of the pool, wherein the neighborhood matrix includes N rows and N columns and wherein each entry (I, J) of the neighborhood matrix located at row I, column J denotes a count of how many times physical storage device I of the pool has neighbored physical storage device J of the pool;
creating and initializing a disk extent consumed array denoting a disk consumption metric, the array storing a value for each of the N physical storage devices of the pool;
analyzing disks in an extent pool to identify a disk servicing fewest input output operations (I/Os) in the extent pool and allocating a disk extent from the identified disk;
configuring the allocated disk extent as a first disk extent for a first RAID extent and updating the neighborhood matrix and the disk extent consumed array, the mapped RAID extents including the first RAID extent;
analyzing all the disks in the extent pool to identify a valid disk extent that will result in a lowest variance value of neighborhood matrix values; and
allocating the identified valid disk extent and updating the neighborhood matrix and the disk extent consumed array.
2. The method of claim 1 , wherein the two physical storage devices I and J of the pool are neighbors with each other each time a first physical storage portion from physical storage device I and a second physical storage portion from physical storage device J are included in a same mapped RAID extent that is allocated.
3. The method of claim 1 wherein the mapped RAID extents include stripes of the RAID group, and wherein each stripe of the RAID group includes M physical storage portions comprising X, one or more physical storage portions storing user data for said each stripe and Y, one or more physical storage portions storing parity information for said each stripe.
4. The method of claim 1 , wherein a first physical storage device of the N physical storage devices fails and a group X of remaining ones of the N physical storage devices of the pool that have not failed, and the method includes:
determining a first set of one or more physical storage portions of the first mapped RAID extent stored on the first physical storage device that failed; and
relocating each physical storage portion of the first set to a physical storage device of the group X, wherein said relocating is performed in accordance with criteria, said criteria including each physical storage portion of the first mapped RAID extent is stored on a different physical storage device of the group X and said criteria including evenly distributing the first set of one or more physical storage portions among the physical storage devices of group X to involve the physical storage devices of group X in a rebuilding process.
5. A system comprising:
a processor; and
a memory comprising code stored therein that, when executed, performs a method of determining slice sizes comprising:
initializing a neighborhood matrix denoting a distribution of neighboring physical storage portions across the N physical storage devices of the pool, wherein the neighborhood matrix includes N rows and N columns and wherein each entry (I, J) of the neighborhood matrix located at row I, column J denotes a count of how many times physical storage device I of the pool has neighbored physical storage device J of the pool;
creating and initializing a disk extent consumed array denoting a disk consumption metric, the array storing a value for each of the N physical storage devices of the pool;
analyzing disks in an extent pool to identify a disk servicing fewest input output operations (I/Os) disk in the extent pool and allocating a disk extent from the identified disk;
configuring the allocated disk extent as a first disk extent for a first RAID extent and updating the neighborhood matrix and the disk extent consumed array, the mapped RAID extents including the first RAID extent;
analyzing all the disks in the extent pool to identify a valid disk extent that will result in a lowest variance value of neighborhood matrix values; and
allocating the identified valid disk extent and updating the neighborhood matrix and the disk extent consumed array.
6. A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of allocating one or more mapped RAID extents comprising:
creating and initializing a neighborhood matrix denoting a distribution of neighboring physical storage portions across the N physical storage devices of the pool, wherein the neighborhood matrix includes N rows and N columns and wherein each entry (I, J) of the neighborhood matrix located at row I, column J denotes a count of how many times physical storage device I of the pool has neighbored physical storage device J of the pool;
creating and initializing a disk extent consumed array denoting a disk consumption metric, the array storing a value for each of the N physical storage devices of the pool;
analyzing disks in an extent pool to identify a disk servicing fewest input output operations (I/Os) in the extent pool and allocating a disk extent from the identified disk;
configuring the allocated disk extent as a first disk extent for a first RAID extent and updating the neighborhood matrix and the disk extent consumed array, the mapped RAID extents including the first RAID extent;
analyzing all the disks in the extent pool to identify a valid disk extent that will result in a lowest variance value of neighborhood matrix values; and
allocating the identified valid disk extent and updating the neighborhood matrix and the disk extent consumed array.