ReadyNAS: lost data after removing a drive : case #17927967

Oops, I was thinking of another thread when mentioning a disk 3 and 4. Sorry for the confusion

i.g wrote:
As I said before I didn't 'experiment' with the device. My landlord (who is a friend of mine) paid a visit to my flat while I wasn't there. He explained the situation but should have known better as we are both programmers. but that doesn't change the situation does it.

So you shouldn't let other people do this kind of thing especially when you're not around. No it doesn't change the situation

i.g. wrote:
That being said I really can't believe the result of this to be honest. Basically the unit has corrupted itself. It is hardly as though the external situation / sequence of events is that complicated that it couldn't deal with?!

Disks can and do fail at any time. There are rare problems that can happen even when you don't have a problem disk. RAID isn't perfect. Having said that your data may be recoverable depending on wha that issue is.

i.g. wrote:
And to boot it could have destroyed one of my drives....

It wouldn't have destroyed one of your drives. If one of your drives was already failing it could've finished it off though due to the heavy stress on the disks that was initiated.

i.g. wrote:
In regards to backup I consider having a second hard that is being replicated onto a form of backup.

Well it's not. Read the article on preventing catastrophic data loss I linked to. High-availability or redundancy whilst it does provide some protection for your data should never be considered backup due to a variety of possible problems it does not protect against including things like accidental file deletions.

i.g. wrote:

In reference to the manual: "Data can be lost due to a number of events, including natural disaster (for example, fire or flood), theft, improper data deletion, and hard drive failure. By regularly backing up your data, you can recover your data if any of these happen to you". Improper data deletion is obviously a user error, fire a theft is obviously going to result in a loss of data although I don't keep spares of everything I own and leave them at remote locations in case there is a fire or it gets stolen. That leaves the third, hard drive failure. I thought a solution to that was buying a second drive that was replicated to from the first one. Apparently not. Given my scenario there was no hard drive failure. The system has failed and that has resulted in a loss of data."

There could be a problem with the disk. it doesn't have to be dead. There could alternatively be a filesystem problem or some other issue. We can only speculate. I'll have to have another read of the manual sometime. However regardless with the dashboard having backup options I think it's fairly clear what is meant by backups.

i.g. wrote:
So you can't say whether the data can be recovered or not.... Or add anything of value. You would prefer to post about the do's and don't's of backup routines. Thanks for the input.

If one doesn't learn from mistakes one is likely to repeat them. I was trying to point out the error of what was done. Removing a drive and putting it back is not something to do for fun as the disk you remove and readd will be wiped and have to be synced back in. You're assuming you won't have a problem whilst your array is unprotected.