jw@sics.se (Johan Widen) (08/08/87)
A tape block is 1024 bytes. Dump writes blocks that are multiples of this
size. The default blocking factor for 1600 bpi tape is 20. That means that
each block written to the tape is 20*1024 bytes.
Now on to tapes with higher density. I have a cartridge tape and have
been recommended to use a blocking factor of 126. I have perused the kernel
with adb and verified that the driver calls
minphys()
It is my understanding that minphys will ensure that blocks larger than 63
kbytes are split up so that no entity larger than 63 kBytes are written.
Would a blocking factor of 63 be more correct (yes, I notice that 63*2 = 126,
so no great harm is done).
Assuming that you have a fast tape drive, is it more efficient to write
blocks that are an even multiple of the size of a disk block?
--
Johan Widen
SICS, PO Box 1263, S-163 13 SPANGA, SWEDEN
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