badblocks too fast?

[Nerdlinger]

breaking in new system.
I've run smartctl tests short and long.
long took about 20 hours (well, its 8TB, what do you expect....)
running badblocks now.

on one disk, its reporting 61% done after 40 minutes!
on the other disk, its reporting 6% done after 46 minutes.

Really weird. I set the
sysctl kern.geom.debugflags=0x10
before starting.
then I ran
nohup badblocks -wsb 4096 /dev/da0

anyone know why one is so fast and other is so slow?

FreeNAS-9.10.2
48GB registered ECC RAM
Motherboard: supermicro X8DTU-F
2x 8 TB WD Red running in zfs mirror
IBM ServeRAID M1015 in IT mode
SuperMicro SuperServer 6026T-URF

 

[Nerdlinger]

after a few hours, it continues. one disk super fast, other much slower....so the time remaining isn't correct, but one test has already moved on to the second and third set of runs, and the other badblocks run is still poking along....

 

[Arwen]

Don't really have an answer, but you could check the write cache of the disks.
Perhaps one disk has it turned on. I've seen turning on the write cache double
the speed of tasks that were write bound.

But 10 times faster?
Don't think so.

Now if one of the 8TB disks was a Seagate Archive SMR, then bloody well
YES. They are not great performers, (I know, I have one). Except they are
cheaper than "plain" disks, and were more or less the first 8TB disks out.

 

[Nerdlinger]

I did a badblocks to my one of the mirrored boot drives...idiot. no wonder it was so much faster. 32 gb of bad blocks slightly faster than 8TB of badblocks. *sigh* #stilllearning. glad there's no real data on this thing yet.

 

[Arwen]

Yep, that would explain it .

Nice thing about ZFS, it would detect that and if your other mirror
is still good, continue to function 100% normally. You can even
perform the replacement live, no down time needed.

I've also done some similar silly things, (even in the last month).
My DVD & Blu-ray collection has been moved off optical disc,
and put on my media server. Since I have an internal DVD and
and external Blu-ray I can do 2 discs at once. IF I select the
proper source. Of course if I don't select the proper source, I
end up with one useless MP4 file and both taking much longer
while they thrash, (move LASER head alot), my optical media.