Sony DDS-4 Product Description Manual page 82

6. COMMAND SPECIFICATION
Data Compression Log Page Fields:
Supported Parameter Codes in this page and their meanings are as follows:
Code
0001h
0002h
0003h
0004h
0005h
0006h
0007h
0008h
0009h
000Ah
000Bh
Entities Written/Read:
The total number of complete entities written to or read from the tape since the last power-on or Cleaner Log
operation.
Records Written/Read:
The total number of records (both compressed and uncompressed) written to or read from the tape since the last
power-on or Clear Log operation.
Kilobytes to/from Data Compression:
The total number of kilobytes written to or read from the tape since the last power-on or Clear Log operation. For
Kilobytes from Data Compression, this number may be greater than the number of kilobytes transferred to the host
due to readahead.
Logical Entity Size:
The logical size of the last entity written to or read from the tape:
size = number of records in entity x record size in bytes
Physical Entity Size:
The physical size of the last entity written to or read from the tape:
size = entity header length + uncompressed data length
Uncompressed Entities:
The total number of times non-DCLZ entities have been encountered on the tape during read operations since the
last power-on or Clear Log operation.
LOG SENSE Commands
From these figures, the host can calculate the average compression ratio achieved by the drive since the last power-on or
Clear Log operation as follows:
average compression ratio =
Similarly, the host can calculate instantaneous compression ratio achieved by the drive for a particular read or write
command:
instantaneous compression ratio =
Description
Number of entities written
Number of entities read
Number of records written
Number of records read
Kilobytes to data compression
Kilobytes from data compression
Kilobytes to tape
Kilobytes from tape
Logical entity size
Physical entity size
Uncompressed entities
kilobytes to data compression
kilobytes to tape
logical entity size
physical entity size
SONY SDT-10000/SDT-11000 DDS Tape Drive
LOG SENSE
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