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[SOLVED] Please help - Cache Read Only after adding new Drive

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After my 500GB (Samsung Evo 860 btrfs) Cache drive started to go twards 90% full, I got a new 1TB Samsung Evo 860 and added it as a second cache drive.

Now it seems my Cache is mounted as read-only and I can't start any VMs or Dockers which I had on the Cache.

 

I was advised to attach the logs. Can anyone help? I'm kinda lost here :(

 

Clarification:

- The 1TB Disk was added to the cache (raid1 as I've learned now).

- I was happy to see, that the cache seemed to work immideately and resized my vm disk (which is on the cache) and spun it up to start an update which was previously not possible due to missing space *duh* < I'm with stupid...

- during the update in the vm froze (obviously due to unraid setting the array to read only to prevent data loss) and I freaked and came here...

 

my learnings so far:

- search through the forum before touching your unriad if you plan on doing something you have never done before. Someone else has probably done it already...

- the cache is configured as raid 1 per default (had I known before, I wouldn't have just added a 1TB)

- don't be so quick to assume, everything will work on it's own

 

So I guess my question now would be more: What data on the cache might still be salvegable?

 

best regards

 

       steel

primogenitus-diagnostics-20201014-2152.zip

Edited by steelrat
Update to clarify

  • Community Expert

The default btrfs configuration is raid1. With 2 drives, that gives a mirror with total capacity equal to the smaller of the drives.

 

So you have overfilled and corrupted cache since it only has 500G.

 

  • Author

Oh shite...

 

Can I actually resolve that or am I royally scr***?

 

best regards and thank you for the help

 

    Steel

Edited by steelrat
Should have had a coffee before the initial reply :)

4 hours ago, trurl said:

The default btrfs configuration is raid1. With 2 drives, that gives a mirror with total capacity equal to the smaller of the drives.

 

So you have overfilled and corrupted cache since it only has 500G.

 

Adding the second drive in raid 1 would give protection and not more space, but if the 500 G drive was 90% full prior to adding the second drive it should not be overfilled just by adding the second drive.

 

@steelrat Did you add any data to the cache after you added the second drive or did the docker and vm services go south directly after reboot. 

  • Author

There was data added to the cache, I'm afraid to say...

 

regards

 

    Steel

Recovering from that state is out of my ballpark.

@JorgeB Is there any chance for @steelrat to recover whatever was on the cache?

 

 

  • Community Expert

Try this:

-stop the array 

-disable docker and VM services 

-start array, delete/move a couple of GBs from cache then balance to single profile

 

 

  • Community Expert

BTW, if there's nothing else to delete you can delete the docker image, should be enough and it can easily be recreated later.

  • Author
11 minutes ago, JorgeB said:

Try this:

-stop the array 

-disable docker and VM services 

-start array, delete/move a couple of GBs from cache then balance to single profile

 

 

Thank you for the help!

I should be able to free enough space, will try and update the thread.

 

regards

 

   Steel

  • Author
Quote

-start array, delete/move a couple of GBs from cache then balance to single profile

@JorgeB Is this the correct command to balance to single profile?

btrfs balance start -dconvert=single -mconvert=raid1 /mnt/cache

I followed your advice, deleted unnecessary data and should now have enough space to da a balance with the desired outcome.

 

best regards

 

    Steel

Edited by steelrat
typo

  • Community Expert

You can do it in the GUI, click on cache and scroll down to the balance section.

  • Author

Running - keeping my fingers crossed 🤞

  • Author

Yay! Everything up and running again 👍

 

Thank you so much @Kevek79 and @JorgeB as well as @trurl

 

The help was much appreciated!

 

Next Steps for me:

- Save Backup Cache to Array. I hope that (CA Backup / Restore Appdata) will do what I need here.

- Remove the Cache alltogether

- start over with a second 1TB drive in Raid1

 

Anything I forgot?

 

best regards

 

     Steel

  • JorgeB changed the title to [SOLVED] Please help - Cache Read Only after adding new Drive

Good to hear that your Server is back up and running.

Please tag your Thread as (SOLVED) if you feel comfortable that the issue is solved.

 

and BTW - Welcome to the Unraid Forum ;)

 

Archived

This topic is now archived and is closed to further replies.

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