Cache RAID is not utilizing the available space

[Márcio Lima]

I have two SSD's that are setup as my cache drives. 

One has 240GB, the other 480GB. My understanding is that the cache drive will have a maximum of 480GB (double of the smalles drive).

Right now, it is only providing 120GB of space.

 

I tried to balance and rebuild the raid without success.

 

Here's the status of the btrfs:

Data, RAID0: total=119.10GiB, used=117.84GiB Data,

single: total=100.00GiB, used=96.56GiB System,

single: total=4.00MiB, used=48.00KiB Metadata,

single: total=1.01GiB, used=231.70MiB GlobalReserve,

single: total=167.67MiB, used=0.00B

 

The UI says it has 490GB of available space, but it's wrong. I had my VM's paused multiple times when I tried to add a 20GB file.

The real used space is 200GB.

 

Any tips?

Edited October 24, 2020 by Márcio Lima

[itimpi]

The default is RAID1 which means the available space is equal to the SMALLER of 2 dissimilar size disks. It is a known issue that when the disks are of different sizes that BTRFS tends to report space incorrectly.

[Márcio Lima]

I converted it into RAID 0. The smallest one has 240GB.

[trurl]

You should convert it to "single"

 

[Márcio Lima]

Would you please clarify why? I would like to keep the RAID 0 for performance reasons.

[trurl]

Single would give maximum capacity, but according to FAQ raid0 should work as you say. Maybe you have something wrong with the configuration.

 

Go to Tools - Diagnostics and attach the complete Diagnostics ZIP file to your NEXT post in this thread. Maybe @JorgeB will know what is wrong.

[Márcio Lima]

There you go.

 

I will be changing the smallest cache disk with other 2 of the same size, but I'll keep the current configuration for at least a month.

ultimatemachine-diagnostics-20201025-0714.zip

[JorgeB]

Pool has dual data profiles, single and raid0:

 

             Data      Data      Metadata  System              
Id Path      single    RAID0     single    single   Unallocated
-- --------- --------- --------- --------- -------- -----------
 1 /dev/sdb1 100.00GiB  60.55GiB   1.01GiB  4.00MiB    62.01GiB
 2 /dev/sdd1         -  60.55GiB         -        -   386.58GiB

 

Run balance to raid0 again.

[Márcio Lima]

I did that, but it kept the two profiles.

[JorgeB]

Please post diags after balance attempt.

[Márcio Lima]

Thanks everyone for the help, but I ended up removing the 240GB out of frustration for now. I'll buy another 480GB SSD.