bill@ssbn.WLK.COM (Bill Kennedy) (02/03/90)
I have a couple of systems running 2.0.2 and 1.0.6 386/ix using the
ISC wt driver and the Everex 60Mb streaming tape. I am well pleased
with the operation of the driver and the hardware but I have some
questions in case anyone knows the answers.
Using cpio for backups and restores with -C 512000 seems to be a real
resource sink. The system bogs down and becomes very sluggish for
anything else. While that's OK and is probably cpio not being as
efficient as it could, I'd like to improve the performance if I can.
There is a 24 pin RAM chip in a 28 pin socket on the controller with
a jumper next to it. I'm going to guess that the jumper selects the
size RAM chip in use. Does anyone know if a larger capacity RAM could
be put into the socket and have the controller take advantage of it?
If so, what size and what jumper setting? It would seem that a DMA
transfer from a '386 buffer to the controller could be done very
quickly and offload the CPU while the controller plays with the tape.
That stimulates another question regarding DMA. Does anyone know if
the controller is actually using DMA for transfers to and from the
host memory? The channel is in the configuration line for the device
and the jumper on the board is set to match, but with such a heavy
CPU burden I wonder if it's really using DMA.
I have used pax (afio) and it seemed to be a little less of a performance
hit, but not enough to really matter. I've not tried compression before
the cpio since it would seem to just add that much more CPU overhead.
I should emphasize that I am well pleased with what I have, I'm just
wondering if there's any more performance to be had. Since there are at
least four other sites I know that have the same curiosity, I'll suggest
that responses be posted rather than collecting and summarizing, there
are bound to be more than just the four I know. Thanks,
--
Bill Kennedy usenet {attctc,att,cs.utexas.edu,sun!daver}!ssbn!bill
internet bill@ssbn.WLK.COM or attmail!ssbn!bill