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Recovering data if NAS unit fails?

Discussion in 'General NAS Discussion' started by Nettle, Jun 24, 2019.

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  1. Nettle

    Nettle Occasional Visitor

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    If I have a 2-bay NAS unit in Raid 1, and the unit itself - not the drives - fails, how would I go about recovering the data? Do I have to buy another unit of the same manufacturer? That is, is my data captive to their system?

    By comparison, if my Windows PC fails, I can just install the HDD into any other Windows PC and there's my data. But my understanding is that the Ext4 and BRTFs file systems of most commercial NAS's cannot be read by Windows.

    Thanks.
     
  2. Internet Man

    Internet Man Senior Member

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    It could probably be read on a Linux system (maybe even booted from a Live CD).

    I think that the answer depends on what NAS you have and what technologies it uses. Maybe you could look up what others have said about recovering data for your specific model. Your NAS might use a proprietary hardware RAID implementation that would require you to find an identical replacement if it fails. It might also use encryption (unlikely) that is tied to your unique NAS box making the data completely unrecoverable upon failure.

    You should have multiple copies of your data in different places if it is important to you.
     
  3. dosborne

    dosborne Regular Contributor

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    100% If the NAS uses Linux at its core, then most likely, as you say, the drives, and therefore the data, should be accessible.

    In some cases, this is the easiest solution. As previously suggested, you should have a backup regardless. However, it has been my approach, in addition to cloud backup, to have a spare NAS ready to rock and roll, all that is required is to swap the drives over.

    Chances are, if you are using a common brand, then someone has had to try and access the drive data after a NAS hardware failure before so a (google) search should turn up specifics for your unit. Even though my units are for personal use, I tend to do a lot of reading before making a new purchase. I want to know all available hacks, patches, firmware release schedules, recovery procedures, etc well before the unit is in operation (or I fork over the cash for it).
     
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  4. RMerlin

    RMerlin Super Moderator

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    Depends on the NAS. If it's Linux based, there's a good chance that you could plug the disk to a Linux box, and mount the filesystem to recover the content. However if you reuse the disk in a different manufacturer, you will have to wipe out the existing content. So, make sure to recover the data BEFORE putting the disk in a different NAS.

    Major manufacturers like QNAP allows one to migrate disks to a different model without loss of data (having a backup is still highly recommended first). For QNAP here is their supported model upgrade matrix:

    http://docs.qnap.com/nas/4.1/Home/en/index.html?system_migration.htm

    EDIT: also, you might have problems recovering the data if you enabled disk encryption. So once again, nothing beats having proper backups of your data.
     
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  5. dosborne

    dosborne Regular Contributor

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    Depending on the format used by the NAS, you could also install the drive in a windows PC (usually via a usb-sata cable) and with the correct drivers, access the data. In the old days, it was a read-only option. Not sure if it has progressed to read-write now. :)
     
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  6. sfx2000

    sfx2000 Part of the Furniture

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    Always back up the NAS - QNAP and Synology both have SW specifically to back up to an external drive or another NAS... I'm reasonably certain other vendors would have as well.

    For recovery - it can be done, Anandtech has a great article on someone that had to do this first hand...

    https://www.anandtech.com/show/8399/recovering-data-from-a-failed-synology-nas

    Gist of it is - for the most part - most modern NAS will use some variant of Linux Volume Manager (LVM) and EXT4 over MDADM.

    Takes skill and patience...

    It's much easier to just back up the NAS on a periodic basis...
     
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  7. Nettle

    Nettle Occasional Visitor

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    Thank you, everyone, for the many helpful replies.

    OK, moral of the story, backup your NAS. Absolutely. But I wonder if this isn't just shunting the problem down one step. 'Cause with that, now I have ext4 files backed up to compressed files on yet another box (since clearly I'm not backing up back onto the hard drive of my PC.) Cannot be read without the backup software/system.

    I guess what I'm getting at is - all these external storage and back up systems seem to lead to having the data from my nice Windows PC NTFS drives squirreled away in some other format on some other, often proprietary, box, such that re-accessing my external or backed up data is totally dependent on these external systems.

    I understand the back ups - compressing is at the very core of the idea - but I'd be happier if my data existed somewhere in just plain good old fashioned uncompressed Windows ntfs format, so that if everything else went wrong except the drive, I can just pull a drive, plug it into a Windows PC , and there's my data.

    I believe this is called a mirror, and I'm reading about mirroring systems right now. You know what I want? A 2-bay NAS that uses NTFS and automatically mirrors the drives. NOT Raid 1 - which I read will not let me pull one drive and use it like a regular drive because of the Raid directory/file system. No, just plain simple real time mirroring. When you write to disk one, write the exact same thing to disk two. Don't convert them into pooled dynamic hoozit's that can't be used separately - just write twice to two independent disks. But I've gone through a bunch of NAS documentation online and none that I can find offer this. It's always Raid 0/1 or jbod.

    THEN, I want another box that will back up one of the mirrored NAS drives in a compressed format. Probably incremental backups so that if need be I can go back to a certain date.

    Does this exist?

    Thanks.
     
    Last edited: Jun 29, 2019
  8. degrub

    degrub Very Senior Member

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    it is called an external USB3/TB/ etc. drive.
     
  9. dosborne

    dosborne Regular Contributor

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    Using your NAS to store a backup of your laptop, PC or whatever, is a good start but many people use it as an internal cloud storage, without another backup, and that is where the problems arise.

    Backups to a proprietary format should be avoided at all costs. As I'm old, I went through the '80s and '90s where tape backup was the only real possibility. Unfortunately, every manufacturer used their own format so data recovery was almost impossible if the drive had issues, which most did. I learned my lesson back then.

    Storage is cheap so my advice is to, at the very least, make use of the free cloud storage options out there. I use these (such as google drive) for an extra copy of my most critical and important data. Not to mention that it also gives me easy access to it from anywhere. If you are concerned about privacy, then you can encrypt files or zip (or other compression) with a password.

    NEVER consider NAS storage as your only solution. I've seen too many people say "I used a Raid 1" and the unit died and now I lost all my data.

    NAS (well, Raid 1+) give you *some* protection against a drive failure, but that's about it. It doesn't help with a NAS unit failing or someone walking off with your NAS.
     
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