It's been probably asked a lot of times and I did find some threads and the wiki but I'm still not sure which split level to use.

I have a huge Media Library plus Backups, Documents and so on.

If I use Split Level 0 and manually create Media/Movies on two disks in the array, only those will be used for Movies, but if I copy a Movie across, that comes with additional files will the whole folder be on one disk, or will it be split across those 2 disks?

 

I assume you are copying the film in question to a User Share rather than directly to a specific disk share?  If that is the case then at Split level 0 you have no guarantee that all files will remain on the same disk.  Split level 0 means that unRAID can put them on any disk that is part of the share according to the Allocation method settings and the current usage.  If you want to constrain files to stay on the same disk then an appropriate Split Level setting is needed.

 

Having said that if you are using the High Water allocation method which tend to fill up disks in turn they will very likely end up on the same disk even with Split Level 0.  Using the Most Free allocation method is quite likely to end up with them split across multiple drives.

Thanks for the reply.

I did a little more digging and I didn't even knew that I can copy directly to a disk share. That way, I have more control and the user share still lists all stuff from different disks.

I will use this now, so the split level shouldn't matter anymore.

edit: write speeds are good when using Windows Explorer to copy files across. Everything looking great so far.

itimpi is wrong. It will never split between the 2 disks. If you do as you wrote then the whole movie directory you create will be stored on a single disk.

 

Basically, split level 0 means that sub-directories can only be placed onto the disks which contain the existing top-level directories. Or, to put it another way, unRAID will never create a directory on another disk once it exists. So, when you copy a movie to the share and it creates the new sub-directory, that sub-directory will never be duplicated on another disk.

 

It's actually a very good way to do a mixed level share. Just manually create the top level structure for the different file types on all of the disks and then the new sub-directories and files you place will always stay on a single disk.

itimpi is wrong. It will never split between the 2 disks. If you do as you wrote then the whole movie directory you create will be stored on a single disk.

Looking at the documentation you are correct.  I always thought of 0 as disabling Split Level but it appears that is not the case.

 

I'm still confused with the Split Levels.

 

How can I make sure that a Directory tries to stay on one disk, but if the space runs out, another disk will be used? I can plan stuff like Pictures and Movies but something like Time Machine Backups I can't calculate.

 

So what can I do so set up something like this?

To avoid the issue you're worrying about, set a Minimum Free Space for the shares (e.g. your Time Machine backups).    Set this to a SAFE number that you know is "enough" for the backup.    Then, if there's not that much space available on a disk, it won't start a write to it -- it will switch to another disk in accordance with your current allocation method.

 

Time Machine is a good example where you want to INCLUDE only one disk in the share definition. 

And do NOT use a cache drive for the TM share. Write directly to the array.

Makes the free space calculation easy, but more importantly, the way TM works internally, you really should restrict it to a single disk.

 

Time Machine is a good example where you want to INCLUDE only one disk in the share definition. 

And do NOT use a cache drive for the TM share. Write directly to the array.

Makes the free space calculation easy, but more importantly, the way TM works internally, you really should restrict it to a single disk.

 

That works well IF the single included disk is either excluded from other shares; or is large enough that the free space is always enough for the Time Machine backup.    I'd be more inclined to set up the Time Machine share with 2 included disks; but a safe "minimum free space" setting and a "Fill up" allocation method.    That would do essentially the same thing as if you'd restricted it to a single disk ... but would allow UnRAID to expand it to a 2nd disk if it ran out of space on the first disk.

 

I think Time Machine does check the Free Space before doing the Backup - at least I did happen for me on my external Drive once that it wouldn't let me back up my Mac. Guess I will just restrict it for a single disk for the time being.

 

Split Levels are still giving me some headaches, but I can always freely move stuff around using the shell, can't I? And I can always change the split level for future writes as well?

 

Thanks for the answers so far.

Yes, you can freely change split level and allocation method settings.    Note that any changes only apply to future writes.

 

I'm still confused with the Split Levels.

 

How can I make sure that a Directory tries to stay on one disk, but if the space runs out, another disk will be used? I can plan stuff like Pictures and Movies but something like Time Machine Backups I can't calculate.

 

So what can I do so set up something like this?

 

Make the share with a minimum free space and fill-up allocation method could work. Just know it will fill the lowest assigned disk first. You can also initially assign a single disk and then add another disk if the current one is running out of space.