On Sat, Nov 10, 2012 at 5:00 PM, Tim Cook <t...@cook.ms> wrote:
> On Sat, Nov 10, 2012 at 9:48 AM, Jan Owoc <jso...@gmail.com> wrote:
>> On Sat, Nov 10, 2012 at 8:14 AM, Trond Michelsen <tron...@gmail.com>
>> wrote:
>>> How can I replace the drive without migrating all the data to a
>>> different pool? It is possible, I hope?
>> I had the same problem. I tried copying the partition layout and some
>> other stuff but without success. I ended up having to recreate the
>> pool and now have a non-mirrored root fs.
>> If anyone has figured out how to mirror drives after getting the
>> message about sector alignment, please let the list know :-).
> Not happening with anything that exists today.  The only way this would be
> possible is with bp_rewrite which would allow you to evacuate a vdev
> (whether it be for a situation like this, or just to shrink a pool).  What
> you're trying to do is write a block for block copy to a disk that's made up
> of a different block structure.  Not happening.

That is disappointing. I'll probably manage to find a used 2TB drive
with 512b blocksize, so I'm sure I'll be able to keep the pool alive,
but I had planned to swap all 2TB drives for 4TB drives within a year
or so. This is apparently not an option anymore. I'm also a bit
annoyed, because I cannot remember seeing any warnings (other than
performance wise) about mixing 512b and 4kB blocksize discs in a pool,
or any warnings that you'll be severely restricted if you use 512b
blocksize discs at all.

> *insert everyone saying they want bp_rewrite and the guys who have the
> skills to do so saying their enterprise customers have other needs*

bp_rewrite is what's needed to remove vdevs, right? If so, yes, being
able to remove (or replace) a vdev, would've solved my problem.
However, I don't see how this could not be desirable for enterprise
customers. 512b blocksize discs are rapidly disappearing from the
market. Enterprise discs fail ocasionally too, and if 512b blocksize
discs can't be replaced by 4kB blocksize discs, then that effectively
means that you can't replace failed drives on ZFS. I would think that
this is a desirable feature of an enterprise storage solution.

Trond Michelsen
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