Device driver, method and computer-readable medium for dynamically configuring a storage controller based on RAID type, data alignment with a characteristic of storage elements and queue depth in a cache

摘要

A storage controller coupled to a host computer is dynamically configured by a device driver executing in the host computer. The storage controller manages a logical volume for the host using a set of flash-based storage devices arranged as a redundant array of inexpensive disks (RAID). The device driver identifies a RAID type for the logical volume and a queue depth from a stream of I/O commands. For a logical volume in RAID 0, the device driver compares the queue depth to a threshold value and configures the storage controller to process the stream of I/O commands with a first path or an alternative path based on a result of the comparison. For a logical volume in RAID 5, the device driver performs a similar comparison and uses the result to direct the storage controller to use a write back or a write through mode of operation.

主权项

1. A method for dynamic switching of write-back to write-through caching mode in a storage controller managing a logical volume supported by flash-based storage devices exposed to a host as a redundant array of inexpensive disks (RAID), the method comprising:
identifying a RAID type for a logical volume managed by a storage controller; identifying a characteristic of a set of flash-based storage devices coupled to the storage controller; initializing a storage controller driver with an alignment flag and a threshold type; monitoring a stream of write commands to determine whether target addresses identified in the stream of write commands are sequential, and when the alignment flag is set whether data identified in the stream of write commands to be written is in alignment based on the characteristic of the set of flash-based storage devices; determining a measure of queue depth in the storage controller; for a logical volume supported by RAID type 0, using the queue depth to direct the storage controller to use one of a first data path or an alternative data path different from the first data path in the data storage controller; and for a logical volume supported by RAID type 5, using queue depth to direct the storage controller to use a write back mode or a write through mode.