[6.9.2] Filled cache drive and changing caching settings led to all shares disappearing, array seeming offline but not marked such

[codetaku]

Running version 6.9.2.  I have a share named "games".  It was set Cache: Yes.  While copying data to this share, the cache pool got entirely full.  Once I realized this, I changed it to Cache: Prefer.  I then started the Mover.  I realized that might not move all of the data to the array, which is what I wanted, so I changed the setting to Cache: No.  Upon making that change, I was told "Share games deleted."  Proceeding beyond that returned me to the Shares tab, which now had no shares at all listed.  On the main Dashboard, it said "No shares configured."  I opened a web terminal and upon performing "ls /mnt", I received the list of directories there along with an error message:  /bin/ls: cannot access '/mnt/user': Transport endpoint is not connected.  Attempts to ls the individual drives did show the data was still there, but despite the UI saying that the array was 'Online', it could not be accessed in the terminal.

 

I cleared out the data I had copied that filled the cache drive and rebooted the system and all shares re-appeared, retaining all of their settings.  It seems filling the cache drive entirely and messing with the Cache settings while the Mover was running led to something crashing.  Attached are the diagnostics which were collected prior to cleaning up the cache pool and rebooting (so cache was still full, shares did not appear, array showed Online, etc).

maple-diagnostics-20220116-0030.zip

[trurl]

@codetaku

Since this is really a misunderstanding and not a bug, I have to copied it to a thread in General Support and closed the "bug report".

 

Cache-yes shares are moved to the array when mover runs. Unless you run it manually the default is to run it once per day in the middle of the night.

 

Cache-prefer is exactly the wrong setting for your situation. Cache-prefer means you prefer that the files stay on cache, and any files that overflow to the array will be moved to cache when mover runs.

 

Mover ignores cache-no and cache-only shares.

 

So, cache-yes is the correct setting to get files moved from cache to array.

 

[trurl]

If you intend to copy more at one time than cache can hold the best approach is to not cache.

 

Post new diagnostics so we can see what your configuration is now and we can make further recommendations.

 

 

[itimpi]

9 hours ago, codetaku said:

While copying data to this share, the cache pool got entirely full. 

You should set the Minimum Free Space setting for the cache (accessed by clicking on it on the Main tab) to be more than the largest file you expect to copy.    When the free space on the cache falls below this value Unraid will start by-passing the cache and write new files directly to the array.   This should stop the cache getting so full it causes problems.

[trurl]

18 minutes ago, itimpi said:

When the free space on the cache falls below this value Unraid will start by-passing the cache and write new files directly to the array.

Provided the share is set to cache-yes or cache-prefer. Cache-no shares will have no new files written to cache, and cache-only shares will always write to cache even if full.

 

[codetaku]

I think there is a misunderstanding of the issue.  Yes, I am aware I had the caching setting incorrect and also what it should be set to.  The bug I was reporting is that changing the cache setting as I did during the Mover running (which I had manually started) resulted in both the share being completely deleted (including a notification screen telling me it has been deleted as if I had chosen to do so, which was never done, I only changed caching settings) as well as ALL shares disappearing and becoming inaccessible.  I had to reboot the server to get the shares to re-appear.  I am certain that is not expected behavior.