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Managing the AMASS File System
6-00028-01 Rev A Fine-tune Block Size B-5
Correlate with
READ-BLOCK
LIMIT
A SCSI drive writes to tape in a fixed block segment determined
by the READ-BLOCK LIMIT of the drive. This means that at the
end of every write, the last block segment may hold less than
one full block of data. Although this may not, at first, impact
performance, it does waste tape resources if the “average” file
size is small and the -b blocksize has been configured for larger
file sizes. This concept is illustrated below.
Tip
The configurable -b blocksize should evenly divide into the
MAXIOSZ value. This concept is illustrated below.
MAXIOSZ
MAXIOSZ
Size of each tape block
divides evenly into MAXIOSZ.
1/4
Tape
Block
Size
1/4
Tape
Block
Size
1/4
Tape
Block
Size
1/4
Tape
Block
Size
Last segment may be less than full of
client’s data.
Subsequent writes start in this contiguous segment.
If many partially filled segments exist, space is
wasted on the tape.