Systems, devices and methods using a solid state device as a caching medium with an SSD filtering or SSD pre-fetch algorithm

1. A computer-implemented method for determining when to load read I/O operations into an SSD cache medium for a physical storage medium of a data storage system, comprising:

dividing the physical storage medium comprising a plurality of equally-sized data blocks into a plurality of zones, wherein each of the zones comprises a different set of the plurality of equally-sized data blocks;

maintaining an SSD filter bitmap including a plurality of bits, each of the bits of the SSD filter bitmap corresponding to a respective equally-sized data block of the physical storage medium, wherein the SSD filter bitmap comprises a plurality of zone level SSD filter bitmaps, each respective zone level SSD filter bitmap corresponding to a different zone of the physical storage medium;

initially setting each of the bits of the SSD filter bitmap to a first binary value;

receiving a first read I/O operation directed to a particular data block of the physical storage medium;

in response to receiving the first read I/O operation, setting a bit of the SSD filter bitmap corresponding to the particular data block of the physical storage medium to a second binary value;

receiving a second read I/O operation directed to the particular data block of the physical storage medium;

in response to receiving the second I/O operation, loading data for the particular data block into the SSD cache medium;

referencing the SSD filter bitmap to determine whether to search the SSD cache medium; and

allocating memory for the respective zone level SSD filter bitmaps on demand in response to receiving an initial read I/O operation directed to the respective zones of the physical storage medium.

2. The computer-implemented method of claim 1 , further comprising:

determining, using the SSD filter bitmap, that the first read I/O operation is an initial read I/O operation directed to the particular data block of the physical storage medium; and

servicing the first read I/O operation from the physical storage medium, wherein the data for the particular data block is not loaded into the SSD cache medium in response to the first read I/O operation.

3. The computer-implemented method of claim 1 , further comprising:

determining, using the SSD filter bitmap, that the second read I/O operation is a subsequent read I/O operation directed to the particular data block of the physical storage medium;

determining whether the data for the particular data block is stored in the SSD cache medium;

if the data for the particular data block is stored in the SSD cache medium, servicing the second read I/O operation from the SSD cache medium; and

if the data for the particular data block is not stored in the SSD cache medium, servicing the second read I/O operation from the physical storage medium and loading the data for the particular data block into the SSD cache medium in response to the second read I/O operation.

4. The computer-implemented method of claim 1 , further comprising periodically re-setting at least one of the bits of the SSD filter bitmap to the first binary value, wherein the at least one of the bits corresponds to a respective equally-sized data block of the physical storage medium having a frequency of access less than a threshold value.

5. A data storage system, comprising:

a physical storage medium;

an SSD cache medium for the physical storage medium; and

a data storage system computer including a processor and a memory in communication with the processor, the memory having computer-executable instructions stored thereon for determining when to load read I/O operations into the SSD cache medium for the physical storage medium that, when executed by the processor, cause the data storage system computer to:

divide the physical storage medium comprising a plurality of equally-sized data blocks into a plurality of zones, wherein each of the zones comprises a different set of the plurality of equally-sized data blocks;

maintain an SSD filter bitmap including a plurality of bits, each of the bits of the SSD filter bitmap corresponding to a respective equally-sized data block of the physical storage medium, wherein the SSD filter bitmap comprises a plurality of zone level SSD filter bitmaps, each respective zone level SSD filter bitmap corresponding to a different zone of the physical storage medium;

initially set each of the bits of the SSD filter bitmap to a first binary value;

receive a first read I/O operation directed to a particular data block of the physical storage medium;

in response to receiving the first read I/O operation, set a bit of the SSD filter bitmap corresponding to the particular data block of the physical storage medium to a second binary value;

receive a second read I/O operation directed to the particular data block of the physical storage medium;

in response to receiving the second I/O operation, load data for the particular data block into the SSD cache medium;

reference the SSD filter bitmap to determine whether to search the SSD cache medium; and

allocate memory for the respective zone level SSD filter bitmaps on demand in response to receiving an initial read I/O operation directed to the respective zones of the physical storage medium.

6. The data storage system of claim 5 , wherein the memory has further computer-executable instructions stored thereon that, when executed by the processor, cause the data storage system computer to:

determine, using the SSD filter bitmap, that the first read I/O operation is an initial read I/O operation directed to the particular data block of the physical storage medium; and

service the first read I/O operation from the physical storage medium, wherein the data for the particular data block is not loaded into the SSD cache medium in response to the first read I/O operation.

7. The data storage system of claim 5 , wherein the memory has further computer-executable instructions stored thereon that, when executed by the processor, cause the data storage system computer to:

determine, using the SSD filter bitmap, that the second read I/O operation is a subsequent read I/O operation directed to the particular data block of the physical storage medium;

determine whether the data for the particular data block is stored in the SSD cache medium;

if the data for the particular data block is stored in the SSD cache medium, service the second read I/O operation from the SSD cache medium; and

if the data for the particular data block is not stored in the SSD cache medium, service the second read I/O operation from the physical storage medium and load the data for the particular data block into the SSD cache medium in response to the second read I/O operation.

8. The data storage system of claim 5 , wherein the memory has further computer-executable instructions stored thereon that, when executed by the processor, cause the data storage system computer to periodically re-set at least one of the bits of the SSD filter bitmap to the first binary value, wherein the at least one of the bits corresponds to a respective equally-sized data block of the physical storage medium having a frequency of access less than a threshold value.

9. The computer-implemented method of claim 1 , further comprising maintaining a table comprising a plurality of pointers, each of the pointers corresponding to one of the respective zone level SSD filter bitmaps.

10. The data storage system of claim 5 , wherein the memory has further computer-executable instructions stored thereon that, when executed by the processor, cause the data storage system computer to maintain a table comprising a plurality of pointers, each of the pointers corresponding to one of the respective zone level SSD filter bitmaps.