[Tfug] OT: Disk testing

[Bexley Hall]

Hi,

Forgive the OT post ... :<

I'm looking for some ideas on how to hack together
a platform to exercise disk drives.  Newer drives
are so large that a comprehensive surface analysis
takes a considerable amount of time!  So, doing
multiple drives concurrently seems like a natural
decision.

But, the drives will have different geometries,
access characteristics, etc.  I.e. obviously they
can't be tested in lock-step with each other
(no big deal).

If these were SCSI drives, I'd have no problem;
find a big enough JBOD and shove 5, 7, 12, etc.
drives into it and, as The Fat Man would say,
"away you go"!

Unfortunately, they are IDE.  This poses two
primary problems:
- IDE controllers only handle two drives
- IDE isn't designed to be hot swappable
(i.e. unplugging the 'Master' while the 'Slave'
is being exercised can perturb the bus, etc.)

The hot-swap criteria is probably a must have
since you want to be able to start the *next*
disk's test as soon as one disk has finished
(i.e. *while* other disks are still being tested).

The "two drive per controller" issue implies that
testing a lot of drives concurrently becomes
problematic -- assuming you can use the "secondary"
controller in a modern PC (keeping the primary
controller for the application itself), you'd
need to come up with several "IDE controller
cards" just to give you the physical interface
to the machine.  These would all be colocated in
*one* machine so you have a tangle of cables
(which have to be kept short!) in one spot.
Add to that, the probable need for an auxilary
power supply (to keep all of those loads off the
PC's single supply) and you end up with an ugly
mess.  :<

I *think* the only practical solution using
COTS technology is to use a bunch of external
USB disk enclosures (!).  Those that I have
seen seem to query the drive for it's geometry
(vs. hard-coding some values in their own
USB controllers).  So, replacing a drive and
reapplying power should be all that is needed
to "reconfigure" the USB device for the new
disk geometry, etc.

And, since they have USB interfaces to the host,
the cable tangle is minimized -- you can locate the
drives separate from the PC for ease of access
(servicing).  Similarly, each device has its
own power source -- capable of powering one
drive -- so the power *supply* automatically
grows to meet the number of drives being tested!

It seems the only issue here would be USB bottlenecks.
Especially if the I/F's were not USB 2.0.

Can anyone see any flaws in my proposed solution?
Or, can anyone come up with a *better* solution??

Thanks!
--don

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