[nSLUG] USB stick for backup okay?

Mike Spencer mspencer at tallships.ca
Mon Apr 9 01:36:16 ADT 2018

Dop wrote:

> On Tue, 3 Apr 2018, Mike Spencer wrote:
>> Digression: Still turning up problems with the IBM P4 box that's my
>> main computer. Shipped with IDE drive but has 2 plugs on mobo for
>> SATA drives.  After the IDE HD failure in 2016, replacement drive
>> was SATA.  Appeared to work fine.  But then found that large writes
>> to HD (say, copy 1G from USB to HD) bogged the CPU down.  Also,
>> playing a DVD video with mplayer causes the clock to fall behind
>> ca. 6 sec. per minute of video.
> An easy thing to check is whether you have multiple devices sharing
> an interrupt, which is nominally OK but slow interrupt handlers can
> lead to it not being OK. Run
> watch -n .1 cat /proc/interrupts
> in one terminal window then perform a slow operation in another and
> see if most of the interrupts are pegging one IRQ. A quick fix might
> be to switch which socket the SATA drive is plugged in to, or move
> USB devices around.

Hah.  Thanks for that.  watch(1) is a new one for me.

I've been distracted by other things but I did try it while playing a
DVD.  Didn't see anything that didn't make sense.  But whatever that
DVD/clock-slow thing is, it's probably very different from the
big-write bog-down.

Int 0, labeled "timer" ticks all the time, apparently 100 times per
second.  (With -n 1, it updated by 101 every screen update.)  I don't
actually know what that is.  Maybe a hack similar to watch(1) would
reveal that when a DVD is playing, that rate changes?  Unsure what
such an observation would explain, though.

More later.

- Mike

Michael Spencer                  Nova Scotia, Canada       .~. 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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