sw raid1 & dma

[robert na v0jta.net]

>   Jeden je hda a druhy hdc, bezi v udma33 modu, jsou to Segate Barracuda
>   IV a Seagate Barracuda 7200. Zkousel jsem 40 i 80 zilove ide kabely.

  Tady je take neco, sice to je polsky, ale da se tomu rozumet ...
  http://www.linuxfan.pl/sprzet/sprzet-2002/01.2002/548.php3

  Jinak, vse nize uvedene splnujete na te masine? Overclock? Kdyz ten disk
vratite zpet do te stare, funguje bez problemu?


  # Why does my kernel report lots of "DriveStatusError BadCRC" messages?

  * (REG, contributed by Mark Hahn) You may see messages like:

  kernel: hda: dma_intr: status=0x51 { DriveReady SeekComplete Error }
  kernel: hda: dma_intr: error=0x84 { DriveStatusError BadCRC }

  In UDMA modes, each transfer is checksum'ed for integrity (like Ultra2
SCSI, and more robust than normal SCSI's parity checking). When a transfer
fails this test, it is retried, and this warning is reported. Seeing these
warnings occasionally is not unusual or even a bad thing - they just inflate
your logs a little. If this really bothers you, you can comment out the
warning in the driver.
  Seeing lots of these warnings (multiple per second) is almost certainly
a sign that your IDE hardware is broken. For reference, all IDE must:

          o have a cable length of 18" or less
          o have both ends plugged in (no stub)
          o be 80-conductor cable if you're using a mode > udma33.

  IDE modes are generally also generated from the system clock, so if
you're overclocking (for instance, running AGP at 75 MHz), you're
violating IDE specs, and should not expect correct behavior. Similarly,
it's possible for your controller's driver to get timing parameters wrong,
but this is certainly not the first explanation to adopt.

-- 
  .''`.
 : :' :     Robert Vojta  robert na v0jta.net, http://www.v0jta.net
 `. `'
   `-                                                    Debian GNU/Linux