HP Q153090901 Performance Data log page

Performance Data log page

The Performance Data log page is 34h. This log is intended to report data of interest to a user/ application on how efficiently the drive is being used.

Parameter	Description	Length	Updated
0	Repositions per 100 MB	2	After each 100 MB has been physically written
				Commands
1	Data rate into buffer	2	After each data set has been logically written
4	Native data rate	2	Fixed
2	Maximum data rate	2	After each data set has been logically written
3	Current data rate	2	After each data set has been logically written

The Parameter Control Byte is 60h for all the parameters.

All the parameters relate to the current tape. They are all cleared at the start of tape load, except Parameter 4, which is never cleared. All data will be reset when the log page is reset. The parameters are as follows.

Repositions per 100 MB Number of tape direction changes per 100 MB written. The higher the figure the more wear occurs.

Data rate into buffer Rate at which data is entering the buffer (after data compression), given in units of 100 KB/s. This is the true ‘tape’ data rate.

Maximum data rate Given the compressibility of the data that has been sent to the drive, this is the maximum data rate that could be achieved, given in units of 100 KB/s. The figure is calculated based on the compressibility of each dataset received, and datasets that have a compressibility greater than the compression bandwidth of the drive will be ‘capped’.

Current data rate	Rate at which data is being accepted by the drive before compression, given in units of
	100 KB/s.
Native data rate	The native rate (that is, without using compression) at which the drive writes data to
	tape, given in units of 100 KB/s:
	Drive	Value	Native Data Rate
	Generation 1 full-height	96h	15 MB/s	NOTE: These figures are for
	Generation 1 half-height	4Bh	7.5 MB/s	native media types and will
	Generation 2	12Ch	30 MB/s	vary when earlier format
	Generation 3	230h	80 MB/s	media is loaded

LOG SENSE 4Dh 69