[ale] Just an FYI for those using UDMA hard drives and RH 7.2

[James P. Kinney III]

What an arcane problem! Congratulations on getting it resolved. That
took some legwork. 

I can see the reasons for having the option to turn off WV. I take it it
was not documented with the drive. It seems a bit underhanded if the WV
is turned off for benchmarking but will fail under normal conditions
with out it.

So, clearly, RedHat 7.2, and presumably Linux in general, will have a
hard time with this drive unless WV is always on. Is a write verify CRC
check manadatory at all times? Is there an option in /proc/ide that will
allow the WV to be turned off from the Linux OS for speed trials? Does
this drive come with an installation disk for M$?

I don't use any Maxtor drives so my proc shows no WV parameters. I went
digging in "man hdparm" and found a -W flag that is used to toggle the
write caching. No reference to write verify. 

On Tue, 2002-01-15 at 12:08, Michael Smith wrote:
> I have been fighting for the last 2 weeks trying to get my 7.2 machine up 
> for more than 12 hours at a time without a kernel panic and I think I 
> finally got it working...
> 
> I determined that it was a UDMA issue after receiving {DriveStatusError 
> BadCRC} errors in the messages log file.  So I bought 2 new 80 pin, less 
> than 18 inch, ide cables after reading this blurb at 
> http://www.kernel.org/pub/linux/docs/lkml/#s13-3 .  I still received the 
> errors.  So I then moved the hard drives to the bottom and top bays to 
> hopefully reduce any crosstalk.  Still didn't work.  I then moved the power 
> cables as far away from the ide cables as possible.  Still didn't work.
> 
> So now I am thinking that either my controller or my hard drives are bad.  
> I go to the Maxtor site and download Powermax to test the drives.  I 
> perform exhaustive checks with both drives coming out without any errors. I 
> am now at a loss.  
> 
> So I dig a little more on the Maxtor site about the write verify 
> functionality on the hard drive and find out, that for speed, the write 
> verify is turned off after 10 power cycles on the hard drive.  So I 
> downloaded this utility called WVSet from their site and turned the write 
> verify back on permanently and now my machine has been up for 24 hours w/o 
> a kernel panic....
> 
> Here's Maxtor's blurb on Write Verify:
> 
> "Write Verify" performs a Read of the data just written to the hard drive 
> and validates the data via the Cyclic Redundancy Check (CRC), providing 
> additional assurance that the data written to the hard drive was written 
> correctly. When Write Verify is enabled, the WRITE performance of the drive 
> is affected as a read occurs for each write. When disabled WRITE 
> performance is improved as, a read is not performed for each write
> When performing benchmark operations the "write verify" feature should be 
> disabled to insure valid comparisons to other products that do not offer 
> this capability in their product.
> 
> 
> Just an FYI......
> 
> -- 
> Michael Smith
> 
> 
> 
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-- 
James P. Kinney III   \Changing the mobile computing world/
President and COO      \          one Linux user         /
Local Net Solutions,LLC \           at a time.          /
770-493-8244             \.___________________________./

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7 



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