Dear LSM 410 administrators,

when transferring data between harddisks or from harddisk to other
devices, we get a very slow data transfer rate: <~ 1MB/s in contrast to
the theoretical 10 MB/s of fast SCSI, or at least 4MB/s for 2 devices.
This makes it very painful to move data to other computers via removable
media or network.
Up to recently I thought that the limited RAM in our machine was the
problem, because the "free memory" in the system performance monitor
went to zero during transfers (along with the CPU usage going to 100%),
but now I upgraded from 32MB to 96MB and the problem still remains. Now
there is free memory left during transfers, but the CPU usage stays at
100%. To me this seems strange, because the SCSI controller has DMA and
PCI busmastering, so that the CPU should not be involved in data
transfers. Before the RAM upgrade, the motherboard and graphics card
were exchanged for some other (?) reason. Transfer speed before and
after the exchange were the same.
- Has anybody experienced such a problem and found a solution for it?
- Now I suspect communication problem between the EISA/PCI motherboard
and the PCI SCSI card, maybe about DMA or so. Would it make sense to
play around with the EISA configuration utility for the motherboard
(possible dangers?)
- Any other suggestions?

The PC of our LSM 410 has a Pentium 150MHz on an AMI Titan II EISA/PCI
motherboard, and is running under Windows 95. The SCSI card is an
Adaptec 2940 PCI to Fast SCSI. The graphics card is a matrox millenium
PCI. The network card is a 3com 509 ISA, and of course, there is the
matrox board in the EISA version.
The SCSI chain connects 2 harddisks, which are actually UW-SCSI and
connected to the cable via adapters, one Teac 58s(?) CD-R and a 2GB Jaz
drive (all internal). It is properly terminated, and all SCSI-IDs are
different :-) The transfer is as slow, when only the system disk is
connected to the SCSI chain.

Thank you for any suggestions,

Joachim


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   Joachim Walter, Dipl. Phys.
   Institut für Anthropologie und Humangenetik der LMU München
   AG Cremer
   Richard-Wagner-Straße 10/I
   D-80333 München               Tel. +49 - 89-2180-6713
   Germany                       Fax  +49 - 89-2180-6719

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