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Ntouchable

How to rebuild data drive - from parity drive + other data drive

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Context:

Dell R710ii + PERC 6/i - Brought 6 months ago on eBay.

3 x WD Red Drives - 2 Data drives + 1 Parity

Been using Linux for a few years.

 

Earlier this week one of my hard drives failed - one of the 2 data drives. I have a replacement to swap in that has arrived from Amazon.

 

My problem starts after installing a new hard drive:

  • When the drive failed I had to reconfigure them in the Dell Config menu, which gives the drives new ID's.
  • When I tried to assign the drives to the array, it just said "Wrong" next to them.
  • As a result of some Googling I did the following: - Tools > NewConfig > Preserve Current Assignments > All > Proceed.
  • Assigned the drives to their corresponding slots > Tick Parity is already valid:
  • "Warning - If parity is already valid, both data drives must have original data."
  • Cancel

 

Not quite sure how to proceed at this point.

 

How do I rebuild the lost data onto my new hard drive, using the parity drive and my other good data drive?

 

Any help much appreciated.

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Go to Tools - Diagnostics and attach the complete diagnostics zip file to your next post.

 

Do you still have the original disk?

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3 hours ago, Ntouchable said:

When the drive failed I had to reconfigure them in the Dell Config menu, which gives the drives new ID's.

Not familiar with this. Is this some sort of RAID controller?

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One of the reasons raid controllers are not recommended, you can use the invalid slot command, if you now which drive ID is which.

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Diagnostics Zip attached.

 

I still have the original disk.

 

PERC 6/i is some kind of old dell raid controller, which I use to set all the drives up individually. Starting to realise this might not be ideal when something goes wrong...

tower-diagnostics-20190315-1445.zip

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The controller also isn't letting us get any SMART report, another even more important reason to not go down this route.

 

Do you only have a 2 disk array? Parity and disk1?

 

Possibly there wasn't anything wrong with the original disk. How would you know without SMART? Connection problems are much more common than bad disks.

 

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Disk 1, Disk 2, Parity.

 

I use the server as a switch too, so it is currently running with the array stopped.

 

I have the dead disk in my PC at the moment. I have recovered some stuff from the good sectors. A lot of the data is corrupt though.

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Yes, I know which disk is which. I can even mount the remaining data disk in unassigned devices and browse it.

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9 minutes ago, Ntouchable said:

I have the dead disk in my PC at the moment. I have recovered some stuff from the good sectors. A lot of the data is corrupt though.

Just because it is corrupt doesn't mean it is dead or even beginning to fail. If it is in your PC you should be able to easily run some diagnostics on it to tell. The disk manufacturers usually have something you can download for free, and there are other free utilities for this purpose.

 

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3 minutes ago, Ntouchable said:

I can even mount the remaining data disk in unassigned devices and browse it.

You shouldn't do that, mount is only safe if doing it read only, and for example if using btrfs would make the invalid slot procedure fail.

 

If you want to try the invalid slot command do this:

 

-Assign existing disks plus the new disk, I assuming the disk to rebuild is disk2
-Important - After checking the assignments leave the browser on that page, the "Main" page.

-Open an SSH session/use the console and type (don't copy paste directly from the forum, as sometimes it can insert extra characters):

mdcmd set invalidslot 2 29

Replace 2 with 1 if it's disk1 you're rebuilding.

 

-Back on the GUI and without refreshing the page, just start the array, do not check the "parity is already valid" box, disk will start rebuilding, disk should mount immediately but if it's unmountable don't format, wait for the rebuild to finish and then run a filesystem check

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@ Johnnie.black

 

It appears to be working. I will confirm once disk is completely rebuilt.

 

Thank you very much. *fingers crossed*

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Update

 

Everything seems to be working fine. I ran a "Filesystem Check" in Maintenance mode and it came back without any errors.

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