I have a Synology Diskstation 414j at my home that runs RAID 5 across 3 drives. I was curious to see what Diskstation looked like on the inside, so I unscrewed the back, took out the drives, and put the drives back into the correct slots. However, I didn't slide one of the drives back in all the way so the system gave errors once I tried to boot it back up. I pushed the drive the rest of the way and rebooted the system.

After rebooting the system I saw that it recommended rebuilding the array so I attempted to do so. This was the wrong choice because unknown to me, another drive was actually failing. I'm guessing the system didn't detect this drive was failing because we don't use the Diskstation very often. We tried copying data off, but ran into bad sector errors about 100GB in.

What should I do to save the data from the drives and how can I detect a drive failure like this in the future?

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    “What should I do to save the data from the drives and how can I detect a drive failure like this in the future?” - You don’t, you performed to many actions for RAID 5, parity is across all drives and the minimum is 3 drives. So you had a configuration that only allowed for a single drive failure and two drives have essentially failed. Things might have been different had you allowed the RAID to repair things before inserting the drive back into the RAID again. Data recovery services that offer RAID support might be worth it at this point. – Ramhound Apr 22 '20 at 0:32

Your NAS use pretty solid EXT4 file system, and even with unfinished rebuild, Your data is recoverable. The safest possible way if You want to try by yourself is to prepare an additional hard drive (at least 3 x bigger than RAID members). Use some software like UFS Explorer or R-Studio, and make the best possible image of each HDDs. If some of HDDs, had errors in the proces of imaging, skip the bad sectors, and try to finish the image. You need at least 2 intact HDD images for successful recovery of Your data. UFS and R-studio have options to build a virtual RAID from 2 images, and You will recover it. In case You have 2 damaged HDD images, You can still try some combination and if there is not so much bad sectors, You will get some data.

You have to know that this is not the safest possible procedure, because imaging of damaged HDDs (bad sectors) can produce more damage on that HDD.

Another (safe) option is to find some reputable Data Recovery company in Your area. They can make an image of damaged hard drives on special hardware, and read it head by head. Your bad sectors, are probably only on one of the heads. So, they will check damaged HDD, prepare it, copy first good heads, and on the end start the "fight" with damaged one. There are some options to "force" the reading of damaged areas of HDD platter. With good images of RAID members,they will easy make a virtual RAID 5, and recover the data. I hope You will get Your data back.


The data is probably actually intact as the array isn't actually appreciably corrupted. Unfortunately, recovering it isn't going to be easy and will need a lot of disk space.

What you need to do is mount the drives (at least the two good ones) and run a tool that can copy data off a blown but recoverable RAID array. I have previously done this with R-Tools long ago (and it was the only thing that could see my data), there are probably other options also but I have had no reason to look further.

You will need enough space to copy the files to, the data can't go back on the originals in this process. It will read the array the best it can without regard for the fact that it was faulted which should be 100% other than anything that was updated during the rebuild.

One feature of their program that I like is they have a demo that is fully functional except it can only recovery very small files--you can see if it's going to work before you spend a penny.

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