Hitachi Ultrastar 15K450, Specifications

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Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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The number of times that the drive was ready to transfer data to its disk (on a write), but its buffer was empty (i.e.,
had not been filled by the Initiator), thus the disk was forced to take extra revolutions.
• DEVICE CACHE FULL READ HITS
The number of times that all of the data requested by the read operation was obtained from the device read or write
cache.
• DEVICE CACHE PARTIAL READ HITS
The number of times that a portion, but not all, of the data requested by the read operation was obtained from the
device read or write cache. A physical operation to the device media was required to obtain the remaining data.
• DEVICE CACHE WRITE HITS
The number of times that the data associated with a write operation replaces, or is combined with, existing data in the
device write cache, thereby eliminating a write operation.
• DEVICE CACHE FAST WRITES
The number of times that space was available in the device write cache for the data associated with a write operation
and a response was returned immediately.
• DEVICE CACHE READ MISSES
The number of times that none of the data requested by the read operation was obtained from the read cache.
The statistics reported by this page are lost on a self-initiated reset or when the Drive is powered off. Even though the DS field
equals zero, the parameters on this page are not savable.