civileme <[EMAIL PROTECTED]> wrote:
>
> WD drives of the generation you are using do not calculate that same
> CRC for comparison--they store it in their big 600-byte sectors along 
> with the 512 bytes of data.  They may calculate the first in a series 
> of writes, but not all.
>
>The drive is safe enough run at udma2 (33Mhz and 32 byte CRCs) or 
>
> If you cannot put a better drive in that box, a 40-pin cable could
> make a big difference for the safe operation, to force 33MHz or lower 
> transfer speed.

Thanks!
I had already read that WD and UDMA5 give problems but my hard drive 
WD400BB-32CXA was bought in april 2002. Were can I find the generation 
info that my drive has no good CRC checking at UDMA3,4,5? I searched the
Western Digital website (wdc.com) but they don't give that kind of 
information. Do the new WD400BB drives do correct CRC checking?

You say "They may calculate the first in a series of writes, but not
all.": where can I find that kind of insight info, I searched the net 
but apart from some of your postings haven't found much else.

I don't have a 40-pin cable. If I use the hdparm command
hdparm -k1 -d1 -X66 /dev/hda      (66:UDMA2), would this give the same 
effect? Can changing the UDMA setting  with hdparm give problems/errors?
I also downloaded from the WDC website Data Lifeguard Tools that can 
change the udma setting on the hard drive itself. If I used this to 
change the UDMA to 2, would my linux have no problems with this (I'm a 
a little scared to use hdparm or WDC tools, in "man hdparm" they state 
"Use with extreme caution! This feature includes zero protection for 
the unwary, and an unsuccessful outcome may result in severe filesystem 
corruption!") ?

How can I prevent CRC errors? Can an IDE-cable suddenly become bad, or 
experience interference, I read about twisted cables, ...
"The HDD should NOT be mounted near the power supply due to fan issues. 
The fan in the supply causes the HDD to misinterpret CRC-checksums and 
produces CRC-errors. Also, high-speed CD drives should not be near the 
HDD" : fan causing CRC-errors? CD drives ?

How much slower is UDMA2 than UDMA5? (hdparm -t), You said somewhere
that the performance does not differ much?


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