I replaced my 240GB SATA SSD with a 1TB M.2 NVME drive and I use it as cache drive. 

This cache drive is used for appdata, system, isos, VM img, docker img, all good part of the unraid system. 

 

But I also used it for partial downloads (incomplete folder) and for rclone cache. 

Now here's the problem:

 

root@Tower:/tmp# dd if=/dev/zero of=/mnt/user/INCOMPLETE/test1.img bs=3G count=1 oflag=dsync
0+1 records in
0+1 records out
2147479552 bytes (2.1 GB, 2.0 GiB) copied, 4.36276 s, 492 MB/s

 

and if it's outside of the array:

 

root@Tower:/tmp# dd if=/dev/zero of=/mnt/cache/INCOMPLETE/test1.img bs=3G count=1 oflag=dsync
0+1 records in
0+1 records out
2147479552 bytes (2.1 GB, 2.0 GiB) copied, 1.68525 s, 1.3 GB/s

 

 

How can I still have the INCOMPLETE folder but don't have it inside the array?

 

Set the INCOMPLETE share to be Cache: Only.

Edited October 19, 20223 yr by Kilrah

5 minutes ago, Kilrah said:

Set the INCOMPLETE share to be Cache: Only.

 

It is set to only. Even tried prefer. 

 

As I understand this only changes how the mover will treat the folder. 

I want it to be outside of the array but still on the cache drive so I don't have to buy another NVME SSD just for this.

Only will not move anything but it will also put anything new on the cache. There is nothing that will end up on the array that isn't already there if a share is set to cache only and you write to /mnt/user/[share].

Edited October 19, 20223 yr by Kilrah

Cache is always outside the array, you can use the disk share for better performance, map to /mnt/cache inside the server or enable disk shares for SMB.

6 minutes ago, JorgeB said:

Cache is always outside the array, you can use the disk share for better performance, map to /mnt/cache inside the server or enable disk shares for SMB.

 

Disk share would be the case I need better performance from another device on my LAN. That's a good info there.

 

Mapping to /mnt/cache seems to be the answer. 

On Sabnzbd I've mapped to /mnt/cache/INCOMPLETE and the most performance difference I'm seeing is instead of using /mnt/user/rclone_cache is using /mnt/cache/rclone_cache/

 

Is there any complication that can come from using direct disk access instead of the user folder in the cache drive?

I'm aware this is a problem when writting files to disks that are indeed part of the array.

Writing directly to /mnt/cache is fine BUT AFAIK you won't benefit from the "min free space" protection to avoid filling it up to the brim, which should really be avoided.

That's fine, and thanks for the info. 

 

As I use it mostly for incomplete downloads from sabnzbd and for the rclone cache, which is already limited in size, this is fine. 

Sorry to revive this topic but I need to ask one more question.

 

I have replaced my kingston nv1 snvs/1000g for a adata XPG gammix s11 Pro that I was using in another PC.

The XPG is much faster compared to the Kingston, I was getting 3GB/s with it on Windows.

 

The m.2 connection on this motherboard is PCIE 3.0 X4 so it should max out at 32gbit/s and from previews tests with the kingston I was getting 1.3GB/s if writting directly to the cache.

 

After replacing it:

 

root@Tower:~# dd if=/dev/zero of=/mnt/cache/INCOMPLETE/test1.img bs=3G count=1 oflag=dsync
0+1 records in
0+1 records out
2147479552 bytes (2.1 GB, 2.0 GiB) copied, 2.32709 s, 923 MB/s

 

Much slower. 

 

Before I try anything else, this cache drive is formated as BTRFS and I don't remember if the previews one was XFS. 

 

Should I go XFS for this drive to max out it's performance? Or file system matters little in this case?

Answering my own question XFS is faster compared to BTRFS:

 

root@Tower:/mnt/cache# dd if=/dev/zero of=/mnt/cache/test2.img bs=3G count=1 oflag=dsync
0+1 records in
0+1 records out
2147479552 bytes (2.1 GB, 2.0 GiB) copied, 1.59658 s, 1.3 GB/s

 

and doing a different test:

root@Tower:/mnt/cache# dd if=/dev/zero of=/mnt/cache/test.img bs=1M count=5120
5120+0 records in
5120+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 2.34594 s, 2.3 GB/s

 

Almost the same speed I was getting on windows.