Unmounted DATAVol1 and persist

[amine]

Hi teams,
I will be very thankful for helping me with this situation, i have a Qnap Model: TS-853U-RP with 6 disks, it show me always that VolData1 is unmounted and i can only format it.
I have a very valuable informations on it, so please someone assist me with this.

[dolbyman]

no backups? can't be that valuable then

anything that happened? disk failure? power failure?

please do an 'md_checker' via ssh

[amine]

thanks for your replay, in fact the nas was the backup, the data is IRM images of many patients this why i should found a way to recover them.
and yes the problem begin with a general power failure.
md_checker result:
###############
Scanning system...


RAID metadata found!
UUID: 71e9c4f1:6c1b5c62:1807c606:e684b873
Level: raid5
Devices: 5
Name: md1
Chunk Size: 512K
md Version: 1.0
Creation Time: Jan 4 19:14:11 2017
Status: ONLINE (md1) [UUUUU]
================================================================================ ===============
Enclosure | Port | Block Dev Name | # | Status | Last Update Time | Events | Array State
================================================================================ ===============
NAS_HOST 1 /dev/sde3 0 Active Apr 19 13:43:23 2021 1756 AAAAA
NAS_HOST 2 /dev/sdf3 1 Active Apr 19 13:43:23 2021 1756 AAAAA
NAS_HOST 3 /dev/sdc3 2 Active Apr 19 13:43:23 2021 1756 AAAAA
NAS_HOST 4 /dev/sdd3 3 Active Apr 19 13:43:23 2021 1756 AAAAA
NAS_HOST 5 /dev/sda3 4 Active Apr 19 13:43:23 2021 1756 AAAAA
NAS_HOST 6 /dev/sdb3 4 Active Feb 3 12:02:42 2021 1644 AAAAA
================================================================================ ===============
WARNING: Duplicate device detected for #(4)!

[dolbyman]

thanks for your replay, in fact the nas was the backup, the data is IRM images of many patients this why i should found a way to recover them.
and yes the problem begin with a general power failure.

Common misconception , if the NAS is the backup, then the files are still somewhere else (otherwise the NAS is the storage, NOT the backup and you need backups!)

The RAID looks OK, but because you have no backups, contact QNAP for assistance to re-init the Volume/LVM, doing this via forum posts is too risky.

If you ever get your data back, start to make external backups(USB/Cloud/other NAS). They will save your bacon one day.

Also get a UPS to provide backup power during outages and controlled shutdowns of your storage.

[amine]

Thanks a lot, for sure your recommendations will be applied. i hope the support can help me with that.