[PLUG] Stress-testing a hard disk (2)

Keith Lofstrom keithl at kl-ic.com
Fri Sep 4 00:48:10 UTC 2020


On 9/2/20 9:43 PM, Keith Lofstrom wrote:

KL> ... Is there a non-intrusive command-line hard drive test
KL> tool that can stress-test a hard drive for months with
KL> minimal CPU and RAM activity?  ...
 
On Wed, Sep 02, 2020 at 10:30:23PM -0700, Galen Seitz wrote:

GS> ... I don't know how well the SMART tests work over a USB
GS> interface.  I think there was a time when smartctl wouldn't
GS> work over USB, but that may have been solved long ago. ...

Thanks, Galen!

"smartctl" still doesn't work over USB, or anyway not with a
3.10.0 kernel.  Sigh.

GS> There's also the badblocks command.  I don't know how much
GS> it would load your system, but I bet it would be less than
GS> a program like bonnie which tests performance.

"badblocks" DOES work - though I used a wrapper:

e2fsck -cc -f -y /dev/sdc2   # (99% of the hard drive)

This is very slowly grinding away:

   Checking for bad blocks (non-destructive read-write test)
   Testing with random pattern:   0.75% done, 1:24:28 elapsed. (0/0/0 errors)

... and monopolizing one CPU core (load average 1.15), but
otherwise behaving itself.  I estimate that this will take
about 8 days to complete one pass on the 8TB partition.

I presume that shingled writes (necessitating rewrites of
huge blocks of data for every byte written, yikes!) are
responsible for the slow speed.  The USB3 drive must be a
busy little beaver, though it is merely warm to the touch.
Not bad for a fanless plastic case cooled by convection.
 
Shingled write probably won't slow down my intended
use (dirvish/rsync backups) terribly much.  I hope. 
Those transactions are mostly reads, and a zillion
new symlinks in the directories, which I assume are
buffered in RAM by the kernel.  I hope, I hope.

I'll see how this behaves overnight, when backups and spamd
run (using two other drives).  I may have a different
opinion of  e2fsck/badblocks  behavior in the morning.

A month from now, after three or four passes of 
e2fsck/badblocks, I will try some rsync tests, and see
how much that performance suffers.  If shingled write is
the wave of the future, I should be prepared to adapt.

Thanks again!

Keith

-- 
Keith Lofstrom          keithl at keithl.com



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