On Tue, Aug 18, 2015 at 10:48 PM, Qu Wenruo <quwen...@cn.fujitsu.com> wrote:
>
>
> Timothy Normand Miller wrote on 2015/08/18 22:46 -0400:
>>
>> On Tue, Aug 18, 2015 at 9:32 PM, Qu Wenruo <quwen...@cn.fujitsu.com>
>> wrote:
>>>
>>> Hi Timothy,
>>>
>>> Although I have replied to the bugzilla, IMHO it's more appropriate to
>>> discuss it in mail list, as it's not a kernel bug.
>>>
>>
>> All four devices were online.  The "missing" one was a drive that
>> died, which was replaced by a new one, but btrfs wouldn't finish the
>> deletion of the missing device.
>>
> By replaced, did you mean "btrfs replace"? Or just change the physical disk
> without using "btrfs replace"?

Here's what happened:

- A drive started throwing bad sectors.  Somehow this caused metadata
on other drives to get messed up.
- I took that drive offline and mounted degraded (it's a 4-drive RAID1)
- I did a "btrfs add" on a new drive and then a "btrfs delete missing"
- The replacement drive failed during the replacement operation, and
everything went to crap.
- With some help, I got a kernel patch that allowed me to mount the
original three drives with TWO missing devices.
- I added a brand new drive and then did "delete missing" again.  This
time, the first "delete missing" was successful, but it didn't fully
balance the drives, and there was another missing device, so I had to
do a "delete missing" again, and that failed.

I wanted to get this back online and restored from a backup, but I was
willing to keep it this way if people wanted to probe at, in case we
can uncover any btrfs bugs.  So it was suggested to get a metadata
image, but that ran into some kind of bug in btrfs-image.

Currently, I'm restoring from backup, but I have at least a partial
metadata dump.


-- 
Timothy Normand Miller, PhD
Assistant Professor of Computer Science, Binghamton University
http://www.cs.binghamton.edu/~millerti/
Open Graphics Project
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