Error: btrfs_merge_bio_hook+a0 #26746663

Sweet - I'll read up on btrfs, I can't say that I understand anything about it, but I'm making a huge assumption that is where the merge error is coming into play.  Merging the two layers into a cohesive volume.

The /dev/md127 device errored but /dev/md126 took the command, it's processing.  It's possible that it will hit the same problem and never return, but I'll let it spin and see.

Given the output of btrfs fi show, I can't seem to get the correct device to feed into btrfs check <device>

root@3EP133E200327:/# btrfs fi show
Label: '5dbf236c:data'  uuid: b5cd0b0f-723b-4b34-bbae-f19a71206704
        Total devices 2 FS bytes used 9.79TiB
        devid    1 size 8.17TiB used 4.92TiB path /dev/md126
        devid    2 size 8.19TiB used 4.93TiB path /dev/md127

I've tried btrfs check with the uuid above and with the label above.  Both return the error: Could not check mount status: No such file or directory.  I assume if /dev/md126 mounts, then I can use that device.  But the man page says btrfs check checks an unmounted device, so I'm still not sure what device name to feed to btrfs check?

Oh, and I think trying to mount the /dev/md126 device exposed the problem.  The unit feel out of RAIDar, the front panel shows the error message and the telnet session is hung.