A whole 1/3rd of free space is missing on a new and empty cache pool - 3x10TB RAID1

[shEiD]

Like the title says. The weirdest thing - there's %33 of free space is magically missing on a brand new and empty cache pool.

15TB total - 537MB used = 10TB free 🤪

Help please.

 

thepit-diagnostics-20210902-0010.zip

Edited September 2, 2021 by shEiD

[Iker]

From your logs, you created a RAID1 BTRFS pool, however that doesn't work exactly as you expect, mainly because there are different raid1 modes for BTRFS, check this post and configure as you want for most space, performance or data integrity https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices

Edited September 2, 2021 by Iker

[tjb_altf4]

RAID1 is misreported for odd amount of devices, see below

  

On 5/11/2021 at 7:09 PM, JorgeB said:

It's a known btrfs bug with an odd number of devices in raid1, but just the reported free space is wrong, you can still use the full capacity, and free space will be less wrong as the pool gets filled.

 

[shEiD]

@Iker I tried to make sense of it, but failed miserably. 15TB total space says I have a normal RAID1. 10TB free space says I have RAID1C3. How can I actually see what type I have - a console command or webUI?

 

EDIT

is this it?

Data, RAID1: total=799.00GiB, used=787.33GiB
System, RAID1: total=32.00MiB, used=128.00KiB
Metadata, RAID1: total=1.00GiB, used=930.06MiB
GlobalReserve, single: total=512.00MiB, used=0.00B

 

@tjb_altf4 Omg, thank you. Although that does not particularly inspire confidence in btrfs whatsoever 😉 

Fingers crossed, I won't get punished for going with btrfs over zfs 🤞

Edited September 2, 2021 by shEiD