Error: btrfs_merge_bio_hook+a0 #26746663

I have a issue with my RN104 running OS 6.4.2.  It appeared to be working fine on Thursday night.  Friday morning the unit was inaccessible.  The display panel shows btrfs_merge_bio_hook+a0.  The unit does not respond on Raidar and the Admin web page is not accessible.

 

I've worked with NetGear tech support using e-mail over the weekend.  I've been hoping that I could find a white paper or information as to how to troubleshoot.  NetGear suggested that I remove the drives in the unit and insert a scratch drive.  The unit booted and recognized the scratch drive.  Because the head end booted, I have access to the logs.  There does not appear to be any errors or warnings logged before the unit become inaccessible.

 

I have determined that I can remove one drive from the array and boot the unit.  However the remaining three drives will not instance the volume with a drive error.  The remaining three drives show that they need to be formatted to instance a new volume.  It doesn't appear to matter which drive I remove, with three drives the unit will boot but the volume is inaccessible (from my POV, I should get a drive error and if I install a new drive the new drive should become part of the array set). With four drives I always get the btrfs_merge_bio_hook+a0 error. 

 

I did access the boot menu of the unit and perform a disk test, that took over 12 hours.  However I have not seen the result of the test.  The unit was in the btfrs_merge_bio_hook+a0 error the next time I looked at it.

 

I think I've exhausted the ability of Netgear Level 1 support.  I'd like to better understand the problem.  I'd like the data from the disks back, but it's not critical, I can survive the data loss.  But I don't want to find myself in this situation again.  Any suggestions or pointers as to how to debug the issue will help.  I was hoping that I could find a white paper or techinical doc that tells me how to work on the problem.

 

Thanks!