NETGEAR is aware of a growing number of phone and online scams. To learn how to stay safe click here.
Forum Discussion
Birillo71
Nov 03, 2017Aspirant
Recover files using Linux
Hi All, I had a problem with the NAS and I am doing the possible to recover some of the files connecting the disks to a Linux System. I used the following commands as suggested in another discus...
- Nov 17, 2017
The next steps depend on how bad you want the data back, and what risks you want to take.
Of course, you can always contact NETGEAR for Data Recovery, they offer this kind of service as a contract.
While there are some pending sectors on sdf and sdf3 is clearly out of sync (not by much), I don't understand why sdc3 doesn't get included in the RAID array, though it shows bad blocks (mdadm output).
You could try to backup the superblocks (if not already done), then recreate the RAID array. But this could result in irrevocable data loss.
(I'm not 100% sure of what is the best approach at this stage.)
Based on the outputs you provided, I think there are two possibilities.
- Again, this is dangerous territory -
- Either try to recreate the RAID as "--assume-clean".
http://man7.org/linux/man-pages/man8/mdadm.8.html
- Or force the RAID array to assemble.
https://raid.wiki.kernel.org/index.php/RAID_Recovery#Trying_to_assemble_using_--force
For both:
- Either with sde3 sdd3 sdf3
- Or sde3 sdd3 sdc3
In theory, as you "--assume-clean" and only include three members, it shouldn't try to rewrite any block of data (but will overwrite the superblocks). So it shouldn't cause permanent damage. But it's a should.
Parameters from the output you provided:
/dev/sdd3: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 9c92d78d:3fa2e084:a32cf226:37d5c3c2 Name : 0e36f164:data-0 Creation Time : Sun Feb 1 21:32:44 2015 Raid Level : raid5 Raid Devices : 4 Avail Dev Size : 615438961 (293.46 GiB 315.10 GB) Array Size : 923158272 (880.39 GiB 945.31 GB) Used Dev Size : 615438848 (293.46 GiB 315.10 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262064 sectors, after=113 sectors State : active Device UUID : a51d6699:b35d008c:d3e1f115:610f3d0f Update Time : Tue Oct 31 08:32:47 2017 Checksum : 3518f348 - correct Events : 14159 Layout : left-symmetric Chunk Size : 64K Device Role : Active device 1 Array State : AAA. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdc3: Device Role : Active device 2 /dev/sdd3: Device Role : Active device 1 /dev/sde3: Device Role : Active device 0 /dev/sdf3: Device Role : Active device 3
That's what I would try:
# Backup superblocks for each partition - if not already done for partition in /dev/sd[a-f][0-9]; do echo "Backing up superblocks for $partition"; dd if=$partition of=/root/superblocks_$(basename $partition).mdsb bs=64k count=1; done ls -lh /root/superblocks_* # Backup of "mdadm --examine" for each partition - new for partition in /dev/sd[a-f][0-9]; do echo "Backing up mdadm information for $partition"; mdadm --examine $partition > mdadm_-E_$(basename $partition).txt; done ls -lh /root/mdadm_-E_* # Start all healthy RAID arrays - if not already done mdadm --assemble --verbose /dev/md126 /dev/sdc4 /dev/sdd4 /dev/sde5 /dev/sdf5 mdadm --assemble --verbose /dev/md125 /dev/sde4 /dev/sdf4 mdadm --assemble --verbose /dev/md127 /dev/sde6 /dev/sdf6 # Recreate the unhealthy RAID array - new mdadm --create --verbose --assume-clean --level=5 --raid-devices=4 --size=461579136K --chunk=64K --data-offset=131072K /dev/md124 /dev/sde3 /dev/sdd3 missing /dev/sdf3 # Check the integrity - do it again cat /proc/mdstat btrfs device scan btrfs filesystem show btrfsck --readonly /dev/md127 mount -o ro /dev/md127 /mnt btrfs filesystem usage /mnt
Birillo71
Nov 18, 2017Aspirant
Hi jak0lantash,
I tried to assemble using --force and I am now able to access the RAID!!!
Apparently all my files are safe. I am now making a backup.
I really want to thank you for all the support provided in the previuos weeks!!!!!!!!
You really saved me, not only the files!
Gabriele
jak0lantash
Nov 18, 2017Mentor
Great news!!! I'm glad I was able to help and that you got your data back!
First thing first, transfer your data to a new storage AND BACK IT UP! ;)
If you want to read about backups, you can find some information here (discard the bits about ReadyCLOUD): https://community.netgear.com/t5/Using-your-ReadyNAS/My-recommendation-Don-t-use-ReadyCloud-user-home-shares/m-p/1258463/highlight/true#M127461
As a note for other people who stumble across this thread: The steps described here are specific to this exact situation and based on the output of some commands. DO NOT ATTEMPT to just run those commands on your system unless you know what you're doing!
Related Content
NETGEAR Academy

Boost your skills with the Netgear Academy - Get trained, certified and stay ahead with the latest Netgear technology!
Join Us!