[Novalug] How to find hardware device access point

[Jon LaBadie]

On Thu, Oct 29, 2009 at 12:19:31AM -0700, Bryan J. Smith wrote:
> 
...
> 
> > Who actually USES -RAM?
> 
> It has been the optical archiving standard.  -RW was never supposed to exist.
> DVD-RAM lasts 30+ years.  I'm currently at 12 years for some discs, 0 errors.  ;)
> 

I've seen you make this same basic statement several times.
On what do you base the "0 errors" comment?

I ask in the sense of are you actually checking for errors in some
analytical manner or just have not noticed any in occasional usage.

Two examples:

Gene Spafford of Perdue U used to say something like "we have been
backing up our file systems online, live, and in use for years with
no problems caused by the activity"  He did not hesitate to add,
"this does not mean there were no problems, just that we were never
asked to to recover a file that showed any problems".

ZFS was about the first file system in the PC world to use check-
summing during writes and subsequent reads to determine and correct
errors in disk data.  Early on some users complained about the number
of errors that were being reported and attributed it to the software.
They turned out to be normal hardware errors that were never noticed.
Things like bit errors in graphics, audio, video, that would not be
apparent as the data were used.

-- 
Jon H. LaBadie                  jon at jgcomp.com
 JG Computing
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 Reston, VA  20194		(703) 787-0922 (fax)