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I have RAID1 configured as described here

$ sudo mkfs.btrfs -m raid1 -d raid1 /dev/sdb /dev/sdc

Then I mount device and write some data:

sudo mount /dev/sdb /mnt echo "some data" > /mnt/123

I have next picture:

# btrfs fi show Label: none uuid: 01e1a8a1-be78-47d0-8dc2-2e293265b31b Total devices 2 FS bytes used 896.00KiB devid 1 size 3.64TiB used 4.04GiB path /dev/sde devid 2 size 3.64TiB used 4.04GiB path /dev/sdb

Then I unplug one device and see next:

# btrfs fi show warning, device 2 is missing warning, device 2 is missing parent transid verify failed on 22020096 wanted 11 found 8 parent transid verify failed on 22020096 wanted 11 found 8 Ignoring transid failure Label: none uuid: 01e1a8a1-be78-47d0-8dc2-2e293265b31b Total devices 2 FS bytes used 896.00KiB devid 1 size 3.64TiB used 2.01GiB path /dev/sde *** Some devices missing

When I mount /dev/sde device I see no data:

# mount -o degraded /dev/sdb /mnt # cd /mnt # ls

Thus I am not sure that btrfs function normally.

  1. Why I do not see stored data?
  2. Why btrfs fi show displays different info? c/p from posts above:
devid 1 size 3.64TiB used 4.04GiB path /dev/sde VS (after removing one device) devid 1 size 3.64TiB used 2.01GiB path /dev/sde

As you can see used is differ =(

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  • Are you sure you are looking at the same filesystem, you formatted /dev/sdc but examined /dev/sde, so which device was renamed? Commented Oct 7, 2019 at 16:17
  • @TimothyBaldwin: I am sure. The device name was changed when I rescan devices after unplug/plug: sudo echo "- - -" > /sys/class/scsi_host/host2/scan Commented Oct 7, 2019 at 17:13

1 Answer 1

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1

thx to cono. He help me. I have no RAID yet:

# btrfs fi df /mnt Data, RAID1: total=1.00GiB, used=768.00KiB Data, single: total=1.00GiB, used=0.00B System, RAID1: total=8.00MiB, used=16.00KiB System, single: total=32.00MiB, used=0.00B Metadata, RAID1: total=1.00GiB, used=112.00KiB Metadata, single: total=1.00GiB, used=0.00B GlobalReserve, single: total=16.00MiB, used=0.00B

The command suggested at article does not work correctly

So he suggested me make rebalance manually:

# btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt

Now it works as expected:

# btrfs fi df /mnt Data, RAID1: total=1.00GiB, used=512.00KiB System, RAID1: total=32.00MiB, used=16.00KiB Metadata, RAID1: total=1.00GiB, used=112.00KiB GlobalReserve, single: total=16.00MiB, used=0.00B
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