USB boot become unreadable, preparation for reboot

[biwhite]

Hi, my USB boot appears to have become unreadable with errors appearing on dmesg such as:

[1794806.252468] FAT-fs (sda1): Directory bread(block 30551) failed
[1794806.252472] FAT-fs (sda1): Directory bread(block 30552) failed
[1794806.252476] FAT-fs (sda1): Directory bread(block 30553) failed
[1794806.459152] FAT-fs (sda1): unable to read boot sector to mark fs as dirty
[1794811.929409] fat__get_entry: 310 callbacks suppressed
 

/boot is now unreadable, and I can't remount it as the device is no longer present:

 

root@Tower:~# mount /dev/sda1 /boot
mount: /boot: special device /dev/sda1 does not exist.
root@Tower:~# cfdisk /dev/sda
cfdisk: cannot open /dev/sda: No such file or directory
 

I can't find any automatic backups of /boot, apart from one I made manually 11 months ago.  There's evidence that something should have backed it up, with folder structures in /mnt/user/CommunityApplicationsAppdataBackup/Community_Applications_USB_Backup/ and /mnt/user/appdata/Community_Applications_USB_Backup/ but both of these locations only have the folder structure and a couple of 0 byte files with no other content.

 

Can anyone suggest what I ought to take copies of from the running system before I attempt to reboot it, such that I can reconfigure the array and shares if the USB device doesn't work upon reboot?   I can't pull the stick to try in another machine prior to shutting down the NAS as it's plugged into an internal USB socket, so not easily accessible.

 

[FreeMan]

Always a good idea to post the full diagnostics so the experts here can start tracking down all the issues instead of dealing with what may just be a symptom. 

 

Tools -> Diagnostics.  Then post the full zip file.

Edited September 4, 2017 by FreeMan

[Squid]

Odds on the flash drive dropped offline.  Usually can be solved by using a different USB controller on the motherboard.

 

But, you did find an issue with the appdata backup, because technically /boot does still exist when the flash drops offline, but the files would all be unreadable (0 byte).  I'll think about it an issue an update in the coming days to not trash a backup in that situation.