RAID have fallen out of sync or might had a disk failure, were you able to download the logs? It would be best to contact Support through my.netgear.com to have a case created and an expert to escalate the case to be resolved through back-end access.
You may have to pay for Support, Pay per Incident Support may be purchased through them.
Looks like I've lost the volume and trying to restart in Read Only bootup hasn't assisted in recovery. Looking at logs from 2 days ago show no obvious drive errors, but dmesg.log from today shows raid array unable to be rebuilt with loss of 3 of the 4 drives which is astounding! Disappointing that no obvious way of detecting any earlier warning signs. As moderator Stephen says in a previous post raid is not a way of preventing data loss although I did buy NAS for greater security. Fortunately I have a recent backup of critical data with the remainder being a write off. Would I be just as well off having 2 large HDDs one backing up the other (with maybe a 3rd as insurance)?
Would I be just as well off having 2 large HDDs one backing up the other (with maybe a 3rd as insurance)?
Well, you could go with two larger disks in RAID-1 instead of RAID-5. The drives are mirrored, so either one can be used to recover all the content. That does simplify recovery, as you can try booting the system with either disk (removing the other) if the array gets out of sync somehow. It's also simpler to mount the volume in a different linux system.
I've never used local backup jobs myself. There are several failure modes where they won't help (power surges, physical damage to the chassis, software failures). So I back up over the network to a different device. For instance install a large disk in a desktop PC, and use a PC tool to incrementally back up the NAS to the PC disk.
My apology Stephen for addressing your status incorrectly.
Thank you very much for your response and helpful advice.
I had thought of internal and external PC drives as backup for one another with possibly a third external drive updated periodically and kept offsite - although appreciating the offsite one will be out of date between back ups but will preserve some data against local 'disasters'.
I had been using your last suggestion 'install a large disk in a desktop PC, and use a PC tool to incrementally back up the NAS to the PC disk' but didn't always keep this up to date.
Further to my earlier posts I’ve tested all 4 WD red drives with Data Lifeguard Diagnostics and all have passed with no errors.
One thing of note is the power cable, which never gets moved, that is attached to the rear of my RN 10400 seems to have developed a loose/broken connection either in the electric cable itself or within the NAS connector.
Could an intermittent break in the electrical supply cause data corruption and loss of array integrity resulting in inactive or dead volume? The connection is so touchy that even vibration of the desk top sometimes causes an issue to power. I’ve since ordered a new cable and brick hoping this is the problem and not the connection within the NAS.
