ZFS: drive replacement performance

[Mahlon E. Smith]

On Tue, Jul 07, 2009, Freddie Cash wrote:
> 
> This is why we've started using glabel(8) to label our drives, and then add
> the labels to the pool:
>   # zpool create store raidz1 label/disk01 label/disk02 label/disk03
> 
> That way, it does matter where the kernel detects the drives or what the
> physical device node is called, GEOM picks up the label, and ZFS uses the
> label.

Ah, slick.  I'll definitely be doing that moving forward.  Wonder if I
could do it piecemeal now via a shell game, labeling and replacing each
individual drive?  Will put that on my "try it" list.


> > Once I swapped drives, I issued a 'zpool replace'.
> >
> 
> See comment at the end:  what's the replace command that you used?


After the reboot that shuffled device order, the 'da2' changed to that
ID number.  To have it accept the replace command, I had to use the
number itself -- I couldn't use 'da2' since that was now elsewhere, in
use, on the raidz1.  Surprisingly, it worked.  Or at least, it appeared
to.

    % zpool replace store 2025342973333799752 da8


> There's something wrong here.  It definitely should be incrementing.  Even
> when we did the foolish thing of creating a 24-drive raidz2 vdev and had to
> replace a drive, the progress bar did change.  Never got above 39% as it
> kept restarting, but it did increment.

Strangely, the ETA is jumping all over the place, from 50 hours to 2000+
hours.  Never seen the percent complete over 0.01% done, but then it
goes back to 0.00%.


> I'd redo the replace command, and check the output of "zpool status"
> to make sure it's showing the proper device node and not some random
> string of numbers like it is.

Hmm, I'm hunting for it but I don't see it -- know of any way to stop a
replace in progress?

Thanks for the quick reply, Freddie!

--
Mahlon E. Smith  
http://www.martini.nu/contact.html
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