Moving files from cache only to array from command line

[taalas]

Hi!

 

I would like to move some files from the cache drive (/mnt/cache/...) to the array.

 

I tried to mv the files from /mnt/cache/(dir) to /mnt/user/share/(dir) and it seemed to work fine the next time the mover was invoked.

 

Is this in any way problematic, since I faintly remember one should not write to /mnt/user/? That is inly a problem when copying from /mnt/diskn/ though, right?

 

Thanks!

[Squid]

26 minutes ago, taalas said:

I tried to mv the files from /mnt/cache/(dir) to /mnt/user/share/(dir) and it seemed to work fine the next time the mover was invoked

DON'T DO THIS if the net sharename/dir/file works out to be identical between the source and destination.  You will corrupt the file

 

Because you're issuing commands, you are effectively bypassing the share system which sets the use cache settings, include / exclude disks etc

 

What was the problem when mover started?

[taalas]

Thanks for answering Squid.

 

As I said it seemed to work well. The files appeared as "Cache" after i moved them and were moved to a specific disk after the mover processed them. Just to make sure: if anything went wrong only the files I manually moved are in danger, correct?

 

What I am trying to do is move files from a cache-disk only share (appdata in this case) to the array. Since they weren't part of the array to begin with I assumed moving them tu /mnt/user/(share) would be the correct way of letting the mover decide on which disk to put them...

[itimpi]

Mv is NOT mover!

 

Also any folders on / mnt/cache are part of /mnt/user (two different views of the same file.     This is why you must NOT try something like:

  mv /mnt/cache/dirname /mnt/user/dirname

as you end up trying to write the file to itself which can end up truncating it.  
 

If you MUST try something like that then use /mnt/user0 as the target as that excludes the cache disk from the User Share.

[-Daedalus]

Correct. Basically, never mix user shares and disks.

 

/mnt/cache -> /mnt/disk[x] is fine.

/mnt/user/dir1 -> /mnt/user/dir2 is fine.

 

"user" is an abstraction layer used by unRAID between the disks. It includes cache and disks.

[taalas]

@itimpi

I do know that mv and the mover are not the same thing. As I said I moved the files (using mv) from /mnt/cache/ to /mnt/user/ and then the mover daemon moved it to an actual disk on the array.

 

I now understand that this is not good. Hence the question: if files got damaged, does it only affect the files I moved?

 

Is moving the files to /mnt/user0/ the correct way then when moving files directly on the server?

Edited September 15, 2019 by taalas

[Squid]

How about this.

 

This is no "correct" way of doing this.  Only an incorrect way

 

Incorrect:

 

from /mnt/cache/share/file to /mnt/user/share/file

from /mnt/user/share/file to /mnt/user0/share/file

from /mnt/diskX/share/file to /mnt/user/share/file

 

In all of those cases, since effectively the source and destination are identical (1st and 3rd and a possibility on the 2nd), the file gets corrupted

 

So what you are doing is "correct"

 

However, be aware that since you're working from a command prompt, if you move from

 

/mnt/user/share/file to /mnt/user/AnotherShare/file (where share is use cache yes and AnotherShare is use cache no), then the file now in destination AnotherShare is on the cache drive.  This may be in violation of the useCache settings for the AnotherShare, and is due to you bypassing the system, and mover won't touch it.

Edited September 15, 2019 by Squid

[itimpi]

6 minutes ago, taalas said:

@itimpi

I do know that mv and the mover are not the same thing. As I said I moved the files (using mv) from /mnt/cache/ to /mnt/user/ and then the mover daemon moved it to an actual disk on the array.

 

I now understand that this is not good. Hence the question: if files got damaged, does it only affect the files I moved?

 

Is moving the files to /mnt/user0/ the correct way then when moving files directly on the server?

If files get ‘damaged’ then it is reasonably obvious as this particular problem ends up being zero length.

 

when moving files within the server it is recommended that both source and target reference physical drives (or both reference user shares) as this is always safe.  It has the disadvantage that it bypasses the User Share system as you are specifying the target drive explicitly.   The suggestion of using /mnt/user0 is a special case when moving from cache to array when you want the allocation method to be taken into account for placing the target files.

[taalas]

Thanks everyone for clearing this up.

 

To summarize: as I understand it is "safe" to move

 

from /mnt/disk[n]/... to /mnt/disk[m]/...

from /mnt/disk[n]/... to /mnt/cache/... (and vice versa)

from /mnt/user/... to /mnt/user/...

from /mnt/cache/... to /mnt/user0/...

 

When doing this one should be aware that disk includes/excludes etc. could be overruled.

 

If moving files in other ways they can end up being copied to the position they are already in, resulting in zero-length files. This only affects the files moved "incorrectly" not other files on the array.

 

Would this (kind of) sum up what has been said?

[itimpi]

That sounds about right     

[Squid]

If you're curious, here is the bug report regarding this (even though it's not a bug since you're bypassing the system)

 

Edited September 15, 2019 by Squid