Is Rockstor safe to use? Suggested RAID configuration?

[csmall (Colin)]

I keep seeing all this talk of btrfs and raid5/6 so I’m a little confused.

Is rockstor safe to use? Is everyone running with minimal/no parity?

What is the safest raid configuration suggested for rockstor?

[Haioken]

RAID 5/6 is unstable in BTRFS, all other RAID levels are suitable for use.
This is not a fault of Rockstor, but of the underlying FS that Rockstor uses. The RAID 5/6 issues have been well known for a long time, but people continue trying to use them in production environments which give BTRFS a bad name.

I’ve been using Rockstor for quite a while now with no issues, 8 disks (4x3Tb and 4x4Tb) in BTRFS RAID 10.

The ability to dynamically grow/shrink the FS and adding/removing disks on demand has made managing my home NAS significantly more useful.

[phillxnet (Philip Guyton)]

@csmall Hello again.

@csmall

I keep seeing all this talk of btrfs and raid5/6

The outstanding known bugs in the btrfs parity raid levels of 5/6 has come up again on the linux-btrfs mailing list recently:
Linking for context:
https://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg79535.html
but note that our current kernel version is falling behind some of these fixes.

So in that context it’s really just btrfs raid1 and as @Haioken states btrfs raid10. Though I’d favour raid1 for it’s greater simplicity.

ie effectively no change from:

New to Rockstor

@csmall Aside from a backup; one of the non parity raid levels, ie: btrfs raid1 (2 copies on 2 different devices) min drive count 2. or btrfs raid10 (raid1 with striping for performance) min drive count 4. Both levels effectively have single disk failure robustness: see: Redundancy profiles in the Pools section of the docs. Note that currently btrfs is only 2 way in non parity raid levels so irrespective of how many disks you have only 2 copies of the data / metadata will be made, but th…

Hope that helps.

[csmall (Colin)]

Thank you. I hope they eventually sort out 5/6.

Synology uses btrfs for the filesystem but not the raid. Would a configuration like this work better for rockstor until they fix raid5/6 in btrfs?

[Haioken]

Hi @csmall,

I’m not 100% on this, but I think that Rockstor only support mdraid over BTRFS for the boot drive.

I’d strongly recommend against RAID 5/6 in any case - BTRFS or not - It’s a bad concept from the get go. One of the problems that BTRFS faces with RAID 5/6 (the ‘write-hole’ bug) is present in all RAID 5/6 implementations, it’s just a bit more dangerous in BTRFS.

It’s actually present to some degree in all RAID levels - even RAID 10 weighted with an authorative write disk, but it’s far less likely to nuke data in non-parity RAID configs.