BTRFS RAID1, totally useless?

[HellrazorX]

Hello everyone,
To get this thing out of the way first. I know BTRFS is presented as an experimental feature and RAID5 or + is strongly discouraged.

However, BTRFS is one of the available options when installing. I though it would be safe to use RAID1

I tested with two virtualize instances of PVE and got different results, there's one thing for sure:
A vanilla proxmox install on BTRFS raid 1 cannot boot if disk 2 is disconnected...

Does anybody can share their experience when running Raid1 btrfs as Root disk for PVE?

 

[leesteken]

A vanilla proxmox install on BTRFS raid 1 cannot boot if disk 2 is disconnected...

As I understood from another thread, this is "normal BTRFS behavior" and you need to set some BTRFS kernel parameter have it work in a degraded state.
From the Arch Wiki:

You will get the same error if you try to mount a raid array without one of the devices. In that case, you must add the degraded mount option to /etc/fstab. If your root resides on the array, you must also add rootflags=degraded to your kernel parameters.

 

[HellrazorX]

As I understood from another thread, this is "normal BTRFS behavior" and you need to set some BTRFS kernel parameter have it work in a degraded state.
From the Arch Wiki:

Sure. I did this.
This is why I'm asking users to share their experience.
I'm talking about going to the full process of changing a disk etc.
I simply feel like nobody is using it.

After all the time I spent, trying to do so, I ended up with inconsistent/unreliable results.
1. Build raid
2. Change grub, fstab
3. Remove disk fall to rescue mode
I tried DD some stuff out, rebuild btrfs, rebuild grub etc etc repeat
Sometimes I ended up with broken fs (proxmox boots but crashes)

Documentation lacks from everywhere also.
I really wanted to use btrfs, but if I can't find a concise recipe to change a simple disk.
Even if there is, having to change grub cfg and stuff scares me, will have to check back every upgrades...

I'm already switching back to zfs.

 

[LnxBil]

I'm already switching back to zfs.

What was your intention to switch from zfs to btrfs? AFAIK, btrfs is in all feature aspects less or equal to ZFS.

 

[HellrazorX]

What was your intention to switch from zfs to btrfs? AFAIK, btrfs is in all feature aspects less or equal to ZFS.

Possibly less ram intensive. Also not running on ECC on that ''server''.

 

[jdancer]

I run BTRFS RAID-1 on boot drives on 12-year old servers for RAM reasons.

Only run it on equipment you can recover from or don't care about.

 

[LnxBil]

Possibly less ram intensive.

You can also tune ZFS to not use a lot of RAM, BRTFS is just a little more "optimized" with respect to that.

Also not running on ECC on that ''server''.

As pointed out by one of the creators of ZFS (Matt Ahrens), ECC is not a special requirement for ZFS, rather than for EVERY filesystem.