Lately, I have been having poor or erratic behaviour with many of my dockers after several new ones were installed and the 6.2 upgrade so I decided to start fresh from scratch.  Unfortunately, I assigned one of my mostly empty data drives as the first parity drive by accident before bringing the array online, the original parity drive was in the place of the data disk when brought online.  The second I click start array I realized the mistake I had made and immediately stopped the parity sync. 

 

Being that the disk config was now out of order when brought online, unraid would not allow me to reassigned the proper drives to their original spots, so I decided to format the flash drive again and start over from scratch to see what it would let me do. 

 

Well after starting another fresh unraid flash drive, it now lets me assign the drive in their correct original spots, and recognises the parity drive as still valid, but the accidentally assigned data as parity drive as unmountable and needing to be formatted. 

 

Well, I think I made another mistake by formatting the unmountable drive believing it would rebuild the data, I now realise FORMAT never means REBUILD... UGH. 

 

The only data I appear to be missing is the data that was on the fourth, now formatted, drive.

 

The question I have is, I have what appears to be 3 good data drives with a valid parity drive, can I rebuild the data that was originally on that formatted fourth drive or is it now lost? tks

unthunder-diagnostics-20160923-2124.zip

From what I remember from other situations where folks have done the same thing, all of its data on that drive is now toast.  When you started the format, parity was maintained for the array.  Meaning that the parity was updated to so that the array would still be protected in case another disk would fail. And the first thing that the formatting operation does is to destroy the file allocation tables.

 

Unfortunately, this situation can easily happen when an unexpected situation occurs and a minor panic mode ensues.  Often, the user decides that a quick action is necessary if the problem is to be ever fixed.  (Troubleshooting a server while one is tired is also another receipt for disaster!) To prevent situations like this, stop, take a deep breath, and read the manual.  LimeTech now has a link to the manuals on the bottom tool bar at the right end.  If you don't find the answer there or can't understand the process, ask on the forum.

 

Luckily, you said you had only a small amount of data on that drive.  My approach would be print out the Main Page of the GUI with the disk serial numbers.  Then, reset the array configuration without that 'bad' drive.  See here:

 

      http://lime-technology.com/wiki/index.php/UnRAID_6_2/Storage_Management#Reset_the_array_configuration

 

Double (triple check) your assignment of disks.  Do NOT trust parity if you are given that option!!!  Allow parity to rebuild.  Now add that 'bad' disk as a new data disk.  Someone may know of a way to do it faster but this will work.

As Frank noted, when you formatted the drive in a parity-protected array, you lost all possibility of rebuilding the data, as not only was the drive formatted; but parity was updated to reflect that formatting.

 

There's no need to leave that drive out of a new config => just do a New Config and assign the drives as they are now, but do NOT check the "parity is already valid" box, and let it do a new parity sync.  The drive you lost the data from is already a blank, formatted drive, so there's no reason to leave it out of the configuration.

 

Note you could also just leave the configuration as is and do a standard correcting parity check => that will likely find a lot of errors; but when it's done your parity will be fine.    But a New Config and fresh parity sync is a better idea (and will be quicker).

 

I need to be less impatient and ask for help first if I cannot find an answer on the forums.  Thanks frank1940 and garycase, I'm doing the new config and parity sync now.  Now I need to figure out what's missing from CrashPlan.  I had a parity drive fail on in the past, but only needed to replace it and rebuild parity to recover, but I am still not quite sure what I should have done with an unmountable or failed data drive, what steps would have to be taken to rebuild the drive, I haven't found an explanation of what steps to take on a failed drives?

I need to be less impatient and ask for help first if I cannot find an answer on the forums.  Thanks frank1940 and garycase, I'm doing the new config and parity sync now.  Now I need to figure out what's missing from CrashPlan.  I had a parity drive fail on in the past, but only needed to replace it and rebuild parity to recover, but I am still not quite sure what I should have done with an unmountable or failed data drive, what steps would have to be taken to rebuild the drive, I haven't found an explanation of what steps to take on a failed drives?

 

Look at the extreme bottom, right side of the GUI.  Click on the 'manual' button.  That will open up a link to all of the Manuals.  Look the options for the version 6.2 list.  Picking the 'Storage management option would seem to be a good place to start. 

 

Look at the Table of Contents.  Paragraph 3.2.2 ("Replacing Failed Disk(s)") would be my choice to look to find instructions.  Clicking on that link will give your this:

 

          http://lime-technology.com/wiki/index.php/UnRAID_6_2/Storage_Management#Replacing_failed_disk.28s.29

 

And it appears that you have found the right place.  Now if something is unclear, asking for clarification is always a good idea. 

*IF* that drive was formatted with ReiserFS (if not, sorry!), then there's another way to recover lost data, but it's not completely guaranteed (can't recover anything overwritten), and it's a little more technical.  You can use the Check Disk File systems wiki, but you will be working at the command line.  You will need to use the --rebuild-tree option and the --scan-whole-partition option (-S for short).  It will ignore the current format and search the entire drive for all files and folders, and build a new Reiser file system.

*IF* that drive was formatted with ReiserFS (if not, sorry!), then there's another way to recover lost data, but it's not completely guaranteed (can't recover anything overwritten), and it's a little more technical.  You can use the Check Disk File systems wiki, but you will be working at the command line.  You will need to use the --rebuild-tree option and the --scan-whole-partition option (-S for short).  It will ignore the current format and search the entire drive for all files and folders, and build a new Reiser file system.

When my disks were ReiserFS I put in my cache disk (2TB and almost completely full of data) and tried to rebuild a parity drive on it.  I caught my mistake about 2 minutes after the parity sync started.  I used the commands above and got back all but 200GB of data from the drive.  I wish the XFS recovery tools were that good since XFS is better supported in the later linux kernals in unRAID v6.  I was on unRAID v4.5.6 at the time I believe.  Since then I never do anything when I'm rushed.

... I never do anything when I'm rushed.

 

Absolutely the best approach.  Also don't tackle these kind of problems if you're tired or overly frustrated.  Get some rest; chill out a bit; and then decide what you need to do.

 

One simple rule with ANY failed disk issue:  Do NOT do ANYTHING that might result in a write to the disk, as this will notably reduce the likelihood of data recovery.  If you don't know how to proceed, get help from the forum; or from a professional data recovery company.