+
+Host Read Commands |
+Number of host read commands received during the reporting period. |
+
+
+Host Read Blocks |
+Number of 512-byte blocks requested during the reporting period. |
+
+
+Average Read Size |
+Average Read size is calculated using (Host Read Blocks/Host Read Commands). |
+
+
+Host Read Cache Hit Commands |
+Number of host read commands that serviced entirely from the on-board read
+cache during the reporting period. No access to the NAND flash memory was required.
+This count is only updated if the entire command was serviced from the cache memory. |
+
+
+Host Read Cache Hit Percentage |
+Percentage of host read commands satisfied from the cache. |
+
+
+Host Read Cache Hit Blocks |
+Number of 512-byte blocks of data that have been returned for Host Read Cache Hit
+Commands during the reporting period. This count is only updated with the blocks
+returned for host read commands that were serviced entirely from cache memory. |
+
+
+Average Read Cache Hit Size |
+Average size of read commands satisfied from the cache. |
+
+
+Host Read Commands Stalled |
+Number of host read commands that were stalled due to a lack of resources within
+the SSD during the reporting period (NAND flash command queue full, low cache page count,
+cache page contention, etc.). Commands are not considered stalled if the only reason for
+the delay was waiting for the data to be physically read from the NAND flash. It is normal
+to expect this count to equal zero on heavily utilized systems. |
+
+
+Host Read Commands Stalled Percentage |
+Percentage of read commands that were stalled. If the figure is consistently high,
+then consideration should be given to spreading the data across multiple SSDs. |
+
+
+Host Write Commands |
+Number of host write commands received during the reporting period. |
+
+
+Host Write Blocks |
+Number of 512-byte blocks written during the reporting period. |
+
+
+Average Write Size |
+Average Write size calculated using (Host Write Blocks/Host Write Commands). |
+
+
+Host Write Odd Start Commands |
+Number of host write commands that started on a non-aligned boundary during
+the reporting period. The size of the boundary alignment is normally 4K; therefore
+this returns the number of commands that started on a non-4K aligned boundary.
+The SSD requires slightly more time to process non-aligned write commands than it
+does to process aligned write commands. |
+
+
+Host Write Odd Start Commands Percentage |
+Percentage of host write commands that started on a non-aligned boundary. If this
+figure is equal to or near 100%, and the NAND Read Before Write value is also high,
+then the user should investigate the possibility of offsetting the file system. For
+Microsoft Windows systems, the user can use Diskpart. For Unix-based operating systems,
+there is normally a method whereby file system partitions can be placed where required. |
+
+
+Host Write Odd End Commands |
+Number of host write commands that ended on a non-aligned boundary during the
+reporting period. The size of the boundary alignment is normally 4K; therefore this
+returns the number of commands that ended on a non-4K aligned boundary. |
+
+
+Host Write Odd End Commands Percentage |
+Percentage of host write commands that ended on a non-aligned boundary. |
+
+
+Host Write Commands Stalled |
+Number of host write commands that were stalled due to a lack of resources within the
+SSD during the reporting period. The most likely cause is that the write data was being
+received faster than it could be saved to the NAND flash memory. If there was a large
+volume of read commands being processed simultaneously, then other causes might include
+the NAND flash command queue being full, low cache page count, or cache page contention, etc.
+It is normal to expect this count to be non-zero on heavily utilized systems. |
+
+
+Host Write Commands Stalled Percentage |
+Percentage of write commands that were stalled. If the figure is consistently high, then
+consideration should be given to spreading the data across multiple SSDs. |
+
+
+NAND Read Commands |
+Number of read commands issued to the NAND devices during the reporting period.
+This figure will normally be much higher than the host read commands figure, as the data
+needed to satisfy a single host read command may be spread across several NAND flash devices. |
+
+
+NAND Read Blocks |
+Number of 512-byte blocks requested from NAND flash devices during the reporting period.
+This figure would normally be about the same as the host read blocks figure |
+
+
+Average NAND Read Size |
+Average size of NAND read commands. |
+
+
+NAND Write Commands |
+Number of write commands issued to the NAND devices during the reporting period.
+There is no real correlation between the number of host write commands issued and the
+number of NAND Write Commands. |
+
+
+NAND Write Blocks |
+Number of 512-byte blocks written to the NAND flash devices during the reporting period.
+This figure would normally be about the same as the host write blocks figure. |
+
+
+Average NAND Write Size |
+Average size of NAND write commands. This figure should never be greater than 128K, as
+this is the maximum size write that is ever issued to a NAND device. |
+
+
+NAND Read Before Write |
+This is the number of read before write operations that were required to process
+non-aligned host write commands during the reporting period. See Host Write Odd Start
+Commands and Host Write Odd End Commands. NAND Read Before Write operations have
+a detrimental effect on the overall performance of the device. |
+
+
+