Cache pool with multiple drives not working with correct capacity

[nmills3]

I've recently setup my unraid server and have 3 hard drive in the array, 1 for parity and 2 for storage and for cache i started with a 250gb nvme and added a 1TB sata ssd a few days later. Today i've run into an issue where a share that is set to "Use Array: Yes" is telling me it's full when i try and copy to it. unraid shows my cache pool as only half full and my main array has 4TB of storage spare but i keep getting errors when trying to copy files to any share that has the cache enabled because it thinks it's full but also won't pass the files over to the main array

[JorgeB]

4 minutes ago, nmills3 said:

a 250gb nvme and added a 1TB sata

If you're using v6.8 it's a known issue, fixed on v6.9, usable space on cache using the default profile will be 250GB.

[nmills3]

So if i update to 6.9 that should fix the issue. is it recommended to update to RC builds of unraid?

[JorgeB]

Updating will fix the wrong available space being reported, it won't fix the pool being full.

[nmills3]

ok, so 250gb should be the correct capacity then. If i add more cache drives am i just adding more redundancy or is it possible to increase usable space?

[nmills3]

Also will that then fix the issue of it not saving to the main array when the cache is "full"?

[JorgeB]

1 minute ago, nmills3 said:

ok, so 250gb should be the correct capacity then. If i add more cache drives am i just adding more redundancy or is it possible to increase usable space?

 

You can use this to see usable space.

 

2 minutes ago, nmills3 said:

Also will that then fix the issue of it not saving to the main array when the cache is "full"?

That is unrelated, it depends on the settings, use cache must be set "Yes" (or "Prefer") and the minimum free space for both cache and share need to be correctly set.

[nmills3]

18 minutes ago, JorgeB said:

That is unrelated, it depends on the settings, use cache must be set "Yes" (or "Prefer") and the minimum free space for both cache and share need to be correctly set.

Well currently i have a share called game servers and the cache is set to "Yes" so from my understanding that should save to the cache first if possible but if there isn't space then it should save to the array instead. that behaviour wasn't happening

[nmills3]

Also sorry if this is an obvious question but i'm looking at https://carfax.org.uk/btrfs-usage/ should i just leave it on the default settings and change the number of drives and the ammount of storage on them or do i need to set the raid options on the right and the replication details?

[ChatNoir]

26 minutes ago, nmills3 said:

Well currently i have a share called game servers and the cache is set to "Yes" so from my understanding that should save to the cache first if possible but if there isn't space then it should save to the array instead. that behaviour wasn't happening

Cache - Yes saves new files on cache, then Mover move those file to the Array according to the Mover schedule. Note that open files will not be moved.

 

The behavior you describe is Cache - Prefer.

[nmills3]

Just now, ChatNoir said:

Cache - Yes saves new files on cache, then Mover move those file to the Array according to the Mover schedule. Note that open files will not be moved.

 

The behavior you describe is Cache - Prefer.

 

Well i want files to be written to the cache and then moved to the array. so from what the use cache descriptions say i have it on the right mode for the behaviour i'm expecting

 

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.

 

[ChatNoir]

Ok, I misunderstood your previous statement then.  

[JorgeB]

42 minutes ago, nmills3 said:

so from my understanding that should save to the cache first if possible but if there isn't space then it should save to the array instead.

Yes, but only if

1 hour ago, JorgeB said:

minimum free space for both cache and share need to be correctly set.

 

 

 

27 minutes ago, nmills3 said:

should i just leave it on the default settings and change the number of drives and the ammount of storage on them or do i need to set the raid options on the right and the replication details?

Yep.

 

[nmills3]

Ok, i'm seeing where i went wrong here. All of my shares are set to minimum free space 0. I assumed that it meant that unraid would just keep filling the drive until there wasn't enough space for whatever the next file it tried to write was. i've now set it to 5GB for my games server share so if i'm understanding correctly it will now start putting new files onto the array if the cache is already below 5GB but say i was to try and put a 10GB file on when there was 7GB left then that would still give me the out of space error.

[itimpi]

24 minutes ago, nmills3 said:

Ok, i'm seeing where i went wrong here. All of my shares are set to minimum free space 0. I assumed that it meant that unraid would just keep filling the drive until there wasn't enough space for whatever the next file it tried to write was. i've now set it to 5GB for my games server share so if i'm understanding correctly it will now start putting new files onto the array if the cache is already below 5GB but say i was to try and put a 10GB file on when there was 7GB left then that would still give me the out of space error.

 

Yes

[trurl]

It has no way to know how large a file will become when it chooses a disk for it. 

 

You must set Minimum to larger than the largest file you expect. 

 

Also you might consider a different configuration for your cache pool since default raid1 will have wasted space with 2 disks of different sizes. 

 

Or with 6.9 you can have multiple pools