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

[jeff hubbs]

Is this something for the kernel development list?  Having to take a 
permanent performance hit doesn't strike me as a good solution.  Does it 
seem as though Maxtors are the only affected drives?

- Jeff

James P. Kinney III wrote:

> 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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