I had a similar issue some time ago, around the time kernel 4.1.6 was
just there.
In case you don't want to wait for new disk or decide to just run the
filesystem with 1 disk less or maybe later on replace 1 of the still
healthy disks with a double/bigger sized one and use current/older
kernel+tools, you could do this (assuming the filesystem is not too
full of course):
- mount degraded
- btrfs balance start -f -v -sdevid=1 -sdevid=1 -sdevid=1 <mountpoint>
(where missing disk has devid 1)
After completion the (virtual/missing) device shall be fully unallocated
- create /dev/loopX with sparse file of same size as missing disk on
some other filesystem
- btrfs replace start 1 /dev/loopX <mountpoint>
- remove /dev/loopX from the filesystem
- remount filesystyem without degraded
And remove /dev/loopX
On Tue, Oct 20, 2015 at 11:48 PM, Kyle Manna <2blu...@gmail.com> wrote:
> Thanks for the follow-up Duncan, that makes sense. I assumed I was
> doing something wrong.
>
> I downloaded the devel branch of of btrfs-progs and got it running
> before I saw the need for a kernel patch and decided to wait.
>
> For anyone following this later, I needed to use the following to get
> the missing device ID:
>
> btrfs device usage <path>
> ᐧ
>
> On Tue, Oct 20, 2015 at 1:58 PM, Duncan <1i5t5.dun...@cox.net> wrote:
>> Kyle Manna posted on Tue, 20 Oct 2015 10:24:48 -0700 as excerpted:
>>
>>> Hi all,
>>>
>>> I have a collection of three (was 4) 1-2TB devices with data and
>>> metadata in a RAID1 mirror. Last night I was struck by the Click of
>>> Death on an old Samsung drive.
>>>
>>> I removed the device from the system, rebooted and mounted the volume
>>> with `-o degraded` and the file system seems fine and usable. I'm
>>> waiting on a replacement, drive but want to remove the old drive and
>>> re-balance in the meantime.
>>>
>>> How do I remove the missing device? I tried the `btrfs device delete
>>> missing /mnt` but was greeted with "ERROR: missing is not a block
>>> device". A quick look at that btrfs-progs git repo shows that
>>> `stat("missing")` is called, which of course fails since missing isn't a
>>> block device. Nothing other then `btrfs replace` seemed intuitive and
>>> all the docs mention the older command. What's the move?
>>>
>>> Thanks!
>>> - Kyle
>>>
>>> Versions:
>>> Kernel: 4.2.3-1-ARCH
>>> btrfs-progs: 4.2.2-1 ᐧ
>>
>> I believe the current advice given here (that you were likely trying to
>> follow, wrapped link)...
>>
>> https://btrfs.wiki.kernel.org/index.php/
>> Using_Btrfs_with_Multiple_Devices#Replacing_failed_devices
>>
>> ... is dated and no longer works due to code change some time in the past.
>>
>> There's a set of (very) recent patches, to the kernel and userspace both
>> (I just updated userspace and it's in the git devel-branch v4.2.3-49-
>> g4db87a1 I just built, kernelspace, I don't see it in linus-mainline yet,
>> so I'd guess it's in the btrfs-integration patches, to land in the v4.4
>> commit window if not in 4.3 as it's getting late in the cycle for that.
>>
>> btrfs fi show <path>
>>
>> That will list the btrfs component devices together with their devids.
>>
>> Then use the appropriate devid like so:
>>
>> btrfs dev del <devid> <path>
>>
>> The -progs commit is d462081f, by Anand Jain, titled:
>>
>> btrfs-progs: Introduce device delete by devid
>>
>> According to it, the required kernel commit (title only listed) is
>> similar:
>>
>> Btrfs: Introduce device delete by devid
>>
>> You can probably find them on-list if you wish to cherry-pick them into a
>> current version.
>>
>> --
>> Duncan - List replies preferred. No HTML msgs.
>> "Every nonfree program has a lord, a master --
>> and if you use the program, he is your master." Richard Stallman
>>
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