Seagate ST3146954FC, ST373554FC, ST336854FC manual Cheetah 15K.4 FC Product Manual, Rev. B

want to configure the cache to provide large volumes of sequential data in a non-repetitive manner. In this case, the ability of the cache to “look ahead” to the next contiguous segments of sequential data is a good thing.

The Performance Mode (PM) bit controls the way the drive switches the cache buffer into different modes of segmentation. In “server mode” (PM bit = 0), the drive can dynamically change the number of cache buffer segments as needed to optimize the performance, based on the command stream from the host. In “desktop mode” (PM bit = 1), the number of segments is maintained at the value defined in Mode Page 8, Byte 13, at all times. For additional information about the PM bit, refer to the Unit Attention Parameters page (00h) of the Mode Sense command (1Ah) in the Fibre Channel Interface Product Manual, part number 77767496.

Cheetah 15K.4 FC Product Manual, Rev. B 15