NSA310: How to resolve 'DOWN' status for 2 HDDs of 4TB in RAID-1?

rafjel

The NSA310 has only a single bay for a SATA hard disk. The second hard disk is attached external as a eSATA hard disk. This configuration allows to create a RAID-1 volume.

After Windows file history has been written for more than 200 GB, the volume status became "DEGRADED". I unconnected both disks and checked them via CrystalDisk, but could not found any defect. After connecting them again to the nas, the status became "DOWN".

In the log I see "Cannot init applets: (Errno 2) No such file or directory: '/i-data/md0/.zyxel'"

Restarting the NAS with only one of the 2 hard disks, doesn' t change anything! Still status "DOWN" and I can' t see any file via File Browser. The only actions available are Edit, Scan and Delete. Scanning the volume results in "Scan Internal Volume (read-only operation): FAILED"

I would be very happy if I only could recover the files on the volume. Repairing the RAID-1 volume it self is not necessary.

Can anyone help me?

#NAS_Jun_2019

rafjel

Restarting the NAS with only one of the 2 hard disks, doesn' t change anything! Status stays "DOWN" and I can' t see any file via the File Browser. The only actions available are Edit, Scan and Delete. Scanning the volume results in "Scan Internal Volume (read-only operation): FAILED"

I would be very happy if I only could recover the files on the volume. Repairing the RAID-1 volume it self is not necessary.

Mijzelf

Can you connect both disks, open the 'Telnet backdoor', login over telnet (as root, with your admin password), and post the output of

<div>cat /proc/mdstat</div><div><br></div><div>cat /proc/mounts</div><div><br></div><div>mdadm --examine /dev/sd[ab]2</div><div></div>

rafjel

Great you are prepared to help me!

Meanwhile the problem has been solved automatically! In order to understand this recovering I would like to give you more background information of what happened and what has been done.

1. What happened?
   • At the beginning the volume of my nas came in status "Degraded" for a unknown reason. According the User Guide it means that one of the disks (2 times 4 TB in RAID-1 mode) is giving problems.
   • So I checked the status of both disks separately via ChrystalDisk (freeware) by means of an usb-2 interface connection to my laptop, one after the other. Result: both disks were in good condition.
   • I placed both disks back in the nas and after reboot, the volume came in status "Down". It means that it can not be fixed.
   • According a partition manager both disks were empty and their capacity was only 2 TB (instead of 4 TB)! So asked for help.
   • Connecting a 4 TB harddisk through an usb-2 interface? The helper said it was not a good idea to access the disks that way. So I reconnected them again to another computer (a desktop this time) directly to the sata ports on the motherboard. I got the 4 TB back for each disk, but still there were no files to see.
   • And so I contacted you. 
2. What has been done afterwards?
   • I put them back into the nas (like you proposed) and I saw that the volume status was changed to "Degraded" again! This time I could choose to "Recuperate" one of the disks.
     
   • So I did. It took about 12 hours, but finally the volume became "Healthy". I could see the whole content of the disk again, with the status just before the problem began
     

There is just one thing I like to know ... Is it possible that the connection of a 4 TB harddisk to an usb-2 interface can be responsible for a corrupt File Allocation Table of an ext4 file system?

rafjel

@Mijzelf
You asked me to post the output of some commands I have to enter through the 'Telnet backdoor'? Sorry, it 's the first time I hear of.

Because I see on this forum that a lot of problems can be solved via that 'Telnet backdoor', is it prossible for you to give me some instructions to start such a session? Up till now I found how to activate the Telnet Client in Windows. But now, have I to start Telnet by the command prompt or by the webinterface (=internet browser)? And where have I to enter commands like "http://<ip-of-nas>/zyxel/cgi-bin/remote_help-cgi?type=sshd_tdc" that I can read in the link you gave me?

I know I ask mutch, but thanks for a reaction anyway!

And last but not least, according your nickname, do you speak dutch?

Mijzelf

There is just one thing I like to know ... Is it possible that the connection of a 4 TB harddisk to an usb-2 interface can be responsible for a corrupt File Allocation Table of an ext4 file system?

Yes. Except that ext4 doesn't have a FAT, AFAIK. But filesystem corruption is certainly possible. Actually it has nothing to do with the USB2 bus, but with the used SATA-USB chip. A decent chip can work fine on the USB bus (a bit slow, but hey), but a bad chip can either truncate the disk, do a silent sectorsize conversion, or, most bad, wrap around at 1 or 2 TiB. The latter is most bad because you can't know the chip is bad until it happens. The other two will show you a smaller disk, or sector size is wrong.

But now, have I to start Telnet by the command prompt or by the webinterface (=internet browser)? And where have I to enter commands like "http://<ip-of-nas>/zyxel/cgi-bin/remote_help-cgi?type=sshd_tdc" that I can read in the link you gave me?

A http address is always entered in a web browser. It will show you a white page, but meanwhile it has started the telnet daemon, so you can connect.

The 'type-sshd_tdc' is a special one, it starts an ssh daemon. Don't know if that works on more modern firmwares. The link is there, but the daemon might not start due to an incompatible ssl library. The 'type=backdoor' version still works on the latest firmware for the 325.