Re: "logical unit communication failure" c2scan NEC ND-4550A 1.07
"Alexander Noe'" <alexander.noe@s2001.tu-chemnitz.de> wrote:
> > Could you tell us what exact problems you did have?
> > Did you see "logical unit communication falure" too?
>
> On both (!) drives, I got logical unit communication failure as well
> as LOGICAL UNIT COMMUNICATION CRC ERROR (ULTRA-DMA/32). When trying to
> use a Pioneer drive + a Plextor drive on the same channel with the
> same cable, the Pioneer drive continued to work correctly, the Plextor
> drive again reported CRC errors. However, this was not limited to any
>From this report it is obvious that the specific HW combination you are using
bastardizes the data on the cable.
In general: drives that are located at the end of the cable should have less
problems than the ones that are "in the middle" while drives located at the
end of a cable need to be "electrical" better than the ones in the middle.
Exceptions are possible on busses (like ATA) that don't use proper termination.
In case that the drive does not detect a UDMA DRC errors there may be other
reasons (e.g. Linux internal problems). This is why I like to know whether
he is using a 80 wire cable and this is why I did propose to check again using
SchilliX because Solaris is known to report UMDA errors in a way that helps
for further analysis.
> > Did you use a 40 or a 80 wire cable?
>
> 80 wire.
OK, this allows to use UDMA with CRC!
Jörg
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EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
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