Kai Makisara wrote:
I am using the default st module options and not doing anything other than
using 'mt setblk 0'.
Is there anything I can do to get a decent, sustained read rate from these
tapes?
If your system can process the data fast enough and the tape blocks are of
the same size, you can try using fixed block mode and buffered transfers.
This allows the driver to use larger SCSI reads. You have to load the st
module with parameter buffer_kbs=xxx, where xxx is, for instance, 1024 (1
MB buffer). You also have to disable direct i/o with the module parameter
try_direct_io=0 (otherwise buffered transfers are disabled).
Thanks, I tried that, but it makes no difference. I also tried
increasing the buffer_kbs size by doubling it a few times, but that made
no difference either
I have now found out that the tapes were written on an SGI system -
using a fixed block device and the default options to tar. However, I
have to either use 'mt setblk 0' or 'mt setblk 16384' to read anything
from these tapes.
Just to check that nothing is wrong with my system, I can read an LTO-3
tape previously written on my system, using the default options to tar
and the st module - and I get over 40Mb/s on reads, compared with about
400Kb/s I'm getting with these problematic tapes ...
Is there anything else I can do to read these tapes at a decent speed?
Thanks
James Pearson
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