Enabling DMA for disks in Redhat 3.4

[Mike Ault]

Setting the DMA parameters at both the individual drive level

(/etc/sysconfig/harddiskhdc and hardiskhdd had no affect, setting at overall

system level /etc/sysconfig.harddisks had no affect.

 

Thanks for the suggestion though.

 

Here are the drive specs, it should be capable if much higher transfer rates
than 5 MB/sec:

 

Performance Specifications

  Rotational Speed 7,200 RPM (nominal)

  Buffer Size 8 MB

  Average Latency 4.20 ms (nominal)

  Contact Start/Stop Cycles 50,000 minimum

  Seek Times (Average)

  Read Seek Time (Average) 8.9 ms

  Write Seek Time (Average) 10.9 ms (average)

  Track-To-Track Seek Time 2.0 ms (average)

  Full Stroke Seek 21.0 ms (average)

  Transfer Rates

  Buffer To Disk 602 Mbits/s (Max)

   Buffer to Host (EIDE)

  - Mode 5 Ultra ATA 100.0 MB/s

  - Mode 4 Ultra ATA 66.6 MB/s

  - Mode 2 Ultra ATA 33.3 MB/s

  - Mode 4 PIO 16.6 MB/s

  - Mode 2 multi-word DMA 16.6 MB/s

 

 I can't get the system to change PIO or DMA modes. It sets to Ultra 2, but
without being able to use DMA it only achieves 5 MB/s.

 

Mike