Re: "*** Some devices missing ***" & "Unable to stat /dev/sdg" error messages

[Goffredo Baroncelli <kreijack@gmail.com>]

On Sunday 24 January 2010, Ronald Kasl wrote:
> Hello, .. what do I do when I get " *** Some devices missing " and " "Unable 
to stat /dev/sdg" , error message after drive is hotswaped or die ?
> 
> this is what I did?
> 1. mkfs.btrfs -m raid1 -d raid10 -L btrfs_label_01  /dev/sda /dev/sdb 
/dev/sdc /dev/sdd /dev/sdf /dev/sdg
> 2. mount -t btrfs -o compress /dev/sda /mnt/btrfs
> 3. figgle around testing  the system , then I tremoved one of the disk 
(/dev/sdg) to see what happen,  which  is when I get the "device missing"  
message in the btrfs-show that is understandable, but I cannot bring the disk 
back after it's "live" again .... the FS worked just fine without the disk, I 
just don't know how to bring it back to the btrfs pool of disks 
> 
> # btrfs-show
> failed to read /dev/sdg1
> failed to read /dev/sdg
> failed to read /dev/sr0
> Label: btrfs_label_01  uuid: 0135dae3-61d8-430e-80ba-3e254d404371
>     Total devices 6 FS bytes used 28.00KB
>     devid    1 size 931.51GB used 1.02GB path /dev/sda
>     devid    2 size 931.51GB used 1.00GB path /dev/sdb
>     devid    3 size 931.51GB used 2.00GB path /dev/sdc
>     devid    4 size 931.51GB used 2.00GB path /dev/sdd
>     devid    5 size 931.48GB used 1.01GB path /dev/sdf
> 
>     *** Some devices missing
> 
> 4. I tried what is on the wiki under "replacing failed devices, but I
> was getting nowhere since I'm getting "Unable to stat /dev/sdg" error
> message when I'm trying to remove the failed device.
> 
> this is what I did
> umount /mnt/btrfs 
> mount -o degraded /dev/sda /mnt/btrfs
> btrfs-vol -r /dev/sdg /mnt/btrfs
               ^^^^^^^^
> . then I get the  "Unable to stat /dev/sdg"  message

It should be (see 
http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices 
"Replacing Failed Devices")

	# btrfs-vol -r missing /mnt/btrfs

But on my machine raised a segmentation fault.

BR
Goffredo


> 5. I hotswap the disk back to its bay, but the drive still did not show up 
.. it just keept "missing" until I reboot the system, then I could mount it 
... yet after the reboot I had those "
> mount: wrong fs type, bad option, bad superblock on /dev/sda ..." error 
messages untill I did something and then it work (I guess I had to run the 
btrfsctl -a command that showed all the disk present)
> 
> any idea what to do to bring hotswaped drive back to to system?  thanks!!
> 
> btw. do I need to create a partition with fdisk to use the disks with btrfs 
-- first I just used the new disk without creating partition on them, but then 
I read some howto and there was stated that one needs to create a partition 
first --- I tried that and I had the same problem described above and it seems 
that btrfs doesn't care
> 
> thanks!!!
> 
> 
> 
> http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices
> 
> Goffredo Baroncelli wrote:
> > On Sunday 24 January 2010, 0bo0 wrote:
> >   
> >> after a simple reboot,
> >>     
> >                  ^^^^^^
> > Have you do
> >
> >   # btrfsctl -a
> >
> > before mounting the filesystem ? This command scans all the block devices 
> > searching the btrfs volume. So when you mount a device of an array the 
system 
> > is able to retrieves the others.
> >
> > [..]
> >
> >   
> 
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