Running AS/400 with cover off and care of Drives

Hi list,
I was wondering if you can advise me as to whether I should
be running my Model500 with the rounded rear cover on or off.
I could find no specific IBM reference as to what is the correct way but am
I correct in assuming that I should run with the rear cover attached as this
acts as a shield to circulate the air back towards
the cards etc.

Another question is Harddrive care--my model 500 has 18gig total
2 x 6606, 2 x6607, 1x 6713.Are any of these models prone to sticking after
long powerdwn periods.
Since I have the machine at home for the purpose of playing with the project
lightening toolkit I only powerup one day a week for aboubt 4 hours at a
time--How much of a risk Im I taking--I know
Quantem SCSIdrives on PCs are really bad,but IBM drives are
much more reliable(I only use SCSI Ultrastars on my PCs and have
never had a failure--they get a real thrashing to!
What I dont know is how good the AS/400 drives are compared
to the IBM ultrastar PC drives,I have heard a rumor that the AS/400s are top
end Ultrastars with a special logic board??

My friend Andree says you should never
powerdown because spinning the drives does not cause the wear and tear its
the cold starts--in fact he almost guarentied in theory that if you left a
brand new or near new IBM drive in its box for years
it would be useless as the bearings would be stuck--stranglely
enough he has recovered data for clients by carefuly taking apart and
spinning by hand to give a quick start and then transfering the data on to
another drive and throwing the damaged one away

Dave

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