New to unraid and I am on 6.7.0-rc7

 

I was reading through the manual and when I got to the shares I noticed some of the info does not correlate to what is on the GUI.

https://wiki.unraid.net/index.php/UnRAID_Manual_6#User_Shares_2

 

Allocation Method

Manual says Most-Free, High-Water and Split Level whereas the GUI shows High-water, Fill-up, Most Free

(edit: I guess it just looks like Split Level is part of Allocation in the docs, but it really isn't. Just needs better separation I guess)

 

Then it talks about setting Split Level to a number, but in the GUI not only is Split Level not listed as an Allocation Method, but it shows a drop down list of options.

 

It also talks about Export Mode as a parameter, but it doesn't exist on the add user share page.

 

No mention of Use Cache Disk or Enable COW.

 

Speaking of Use Cache Disk... the Yes and Prefer options are confusing. For Yes it says if it writes to the array, it will transfer from the cache to the array. Is it just me not understanding, or is there an issue here? 

 

Quote

Yes indicates that all new files and subdirectories should be written to the Cache disk/pool, provided enough free space exists on the Cache disk/pool. If there is insufficient space on the Cache disk/pool, then new files and directories are created on the array. When the mover is invoked, files and subdirectories are transferred off the Cache disk/pool and onto the array.

 

Prefer indicates that all new files and subdirectories should be written to the Cache disk/pool, provided enough free space exists on the Cache disk/pool. If there is insufficient space on the Cache disk/pool, then new files and directories are created on the array. When the mover is invoked, files and subdirectories are transferred off the array and onto Cache disk/pool.

 

Edited April 11, 20197 yr by dbinott

3 hours ago, dbinott said:

Speaking of Use Cache Disk... the Yes and Prefer options are confusing. For Yes it says if it writes to the array, it will transfer from the cache to the array. Is it just me not understanding, or is there an issue here? 

You not understanding is the issue 😉.

 

Cache disk usage has evolved over the years, the settings and names have evolved but for reasons have not been redone from scratch.

 

Cache originally had 2 settings. Yes or no.

 

Cache yes, was what you set when you wanted to use the cache disk for new writes to the array. This was introduced to help alleviate the slow array writes caused by the parity calculation. Writes to a cache yes user share would go to cache first, then the mover would put them on the parity protected array overnight when speed wasn't an issue.

 

Cache no, was when you didn't care about write speed or wanted the files to immediately go to the parity protected array.

 

Simple, to the point.

 

Then as features were added, it became obvious that some files would be better left on the cache drive, so the setting of cache only was added.

New files were written to the cache drive, and the mover would leave them there.

 

However, cache drives are typically much smaller than the array space, so it became necessary to add a 4th setting, cache prefer. Similar to cache only, but if there wasn't enough space left on the cache drive, new files will write to the array, and when the mover runs, it moves them to the cache drive. This setting has the added benefit of working even if there isn't a cache drive configured, but as soon as a cache drive is added, it can start using it with no setting changes.

 

 

Here is a post from the FAQ with much more detail about the various use cache settings:

 

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?page=2#comment-537383

 

OK, I get it. So in the case of say SABnzbd, I want all the processing done on the cache, but then the media ultimately moved to the array right after processing is done, not overnight. What would the set up be for that use case?

1 hour ago, dbinott said:

OK, I get it. So in the case of say SABnzbd, I want all the processing done on the cache, but then the media ultimately moved to the array right after processing is done, not overnight. What would the set up be for that use case?

I don't use that particular application, but in general, Unraid only moves from cache to array (or array to cache) as already explained in that link I gave. And it is totally based on user shares. So if you want Unraid to do the move then you must arrange for the files to be on a user share that gets moved. You can set the mover schedule to be more frequent or to occur at whatever time you want, but I don't recommend you make it too frequent unless you don't really have a lot of files to move. Mover works best if it can complete the moves without having to contend with other things for use of the disks.

 

You can have an application write to a cached user share, and process on a cached user share, and save the results on a non-cached user share. Or you can let Unraid do the final step with the mover process.

Thanks @trurl