INTELLIGENT HYBRID DRIVE CACHING

摘要

Systems and methods can implement one or more intelligent caching algorithms that reduce wear on the SSD and/or to improve caching performance. Such algorithms can improve storage utilization and I/O efficiency by taking into account the write-wearing limitations of the SSD. Accordingly, the systems and methods can cache to the SSD while avoiding writing too frequently to the SSD to increase or attempt to increase the lifespan of the SSD. The systems and methods may, for instance, write data to the SSD once that data has been read from the hard disk or memory multiple times to avoid or attempt to avoid writing data that has been read only once. The systems and methods may also write large chunks of data to the SSD at once instead of a single unit of data at a time. Further, the systems and methods can write to the SSD in a circular fashion.

主权项

1. A method of caching in a storage system comprising a hard disk and a solid-state drive, the method comprising:
receiving a first read request to read a first page from a hybrid drive comprising a hard disk and a solid-state drive (SSD), the SSD operating as a cache for the hard disk and having a faster read speed than the hard disk; determining whether the first page is located in the SSD; in response to determining that the first page is not located in the SSD, reading the first page from the hard disk, but not caching the first page in the SSD yet to attempt to avoid unnecessarily writing to the SSD should the first page not be read again in the near future, to attempt to reduce wear on the SSD; receiving a subsequent read request to read the first page from the hybrid drive; in response to receiving the subsequent read request:
reading the first page from the hard disk or from memory if the first page is in the memory, andusing a processor to mark the first page for caching in the SSD while waiting to cache the first page in the SSD until other pages have also been indicated as ready for caching, so as to attempt to avoid wastefully writing individual pages to the SSD and thereby attempt to reduce wear on the SSD; in response to determining that a predetermined number of pages have been indicated as ready for caching, including the first page, writing the first page and the other pages indicated as ready for caching to the SSD together so as to efficiently write the pages indicated as ready for caching to the SSD and to attempt to reduce wear on the SSD.