[SOLVED] Switching raid level in btrfs

pums974 · 2015-05-05 21:55:29

I have a multidevice btrfs partition for my root filesystem
I would like to try different raid level (I have 6 disks)

I have :

$ btrfs fi df /
Data, RAID0: total=18.00GiB, used=17.08GiB
System, RAID1: total=32.00MiB, used=16.00KiB
Metadata, RAID1: total=3.00GiB, used=1.28GiB
GlobalReserve, single: total=416.00MiB, used=0.00B

I do :

$ sudo btrfs balance start -dconvert=raid10 -mconvert=raid10 /

And I don't understand why I still have:

$ btrfs fi df /
Data, RAID0: total=18.00GiB, used=16.91GiB
System, RAID1: total=32.00MiB, used=16.00KiB
Metadata, RAID1: total=2.00GiB, used=1.28GiB
GlobalReserve, single: total=416.00MiB, used=0.00B

Why can't I change my raid level ?
Am I doing something wrong ?

EDIT - SOLVED :
No, I wasn't doing anything wrong,
that was due to a bug in the linux kernel 4.0.0

Last edited by pums974 (2015-05-07 06:38:38)

WorMzy · 2015-05-05 22:32:32

As far as I can tell you're not doing anything wrong. Is there anything in dmesg?

nstgc · 2015-05-05 22:33:22

Could you post the output of both "$ sudo btrfs balance start -dconvert=raid10 -mconvert=raid10 /" and "dmesg|tail"? That should have worked. I've done several times in the last 3 months myself.

It may also help to post "journalctl |grep BTRFS" or at least some of it.

pums974 · 2015-05-06 07:06:17

Looking at journalctl -b |grep BTRFS
At boot time, I see normal things

mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 5 transid 20175 /dev/sde5
mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 4 transid 20175 /dev/sdd5
mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 6 transid 20175 /dev/sdf5
mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 2 transid 20175 /dev/sdb5
mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 3 transid 20175 /dev/sdc5
mai 04 20:26:38 Grand-PC kernel: BTRFS: device fsid 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9 devid 1 transid 20175 /dev/sda5
mai 04 20:26:38 Grand-PC kernel: BTRFS info (device sda5): disk space caching is enabled
mai 04 20:26:38 Grand-PC kernel: BTRFS info (device sda5): disk space caching is enabled
mai 04 20:26:38 Grand-PC kernel: BTRFS: has skinny extents

During the balance, he seems to be doing something, with some

mai 05 23:23:02 Grand-PC kernel: BTRFS info (device sda5): found 10716 extents
mai 05 23:23:09 Grand-PC kernel: BTRFS info (device sda5): found 10716 extents
mai 05 23:23:09 Grand-PC kernel: BTRFS info (device sda5): relocating block group 199812448256 flags

same things on dmesg

nstgc · 2015-05-06 11:32:28

That's actually normal, you want to be seeing that.

Hmm, so it is doing a balance, but the end result is the same raid level. Weird.

[edit] How about after the balance has finished? What sort of dmesg/journalctl messages are you seeing?

Also could you post the output of "# btrfs fi sh"? I don't think this is the cause, but sometimes I've found if there isn't enough free space of the volume converts can go wrong.

Last edited by nstgc (2015-05-06 11:34:56)

pums974 · 2015-05-06 12:25:38

There is nothing else in dmesg/journalctl.

And I think, I have enough free space

Label: 'root'  uuid: 60fc2276-29c5-40f8-bc3e-15b2d1fb9ac9
	Total devices 6 FS bytes used 23.86GiB
	devid    1 size 100.00GiB used 5.03GiB path /dev/sda5
	devid    2 size 100.00GiB used 5.00GiB path /dev/sdb5
	devid    3 size 100.00GiB used 6.00GiB path /dev/sdc5
	devid    4 size 100.00GiB used 7.00GiB path /dev/sdd5
	devid    5 size 100.00GiB used 6.00GiB path /dev/sde5
	devid    6 size 100.00GiB used 5.03GiB path /dev/sdf5

df -h
/dev/sda5          600G     26G  574G   5% /

WorMzy · 2015-05-06 13:22:15

Strange, I can convert a cobbled together array of loop devices with no problems. I haven't seen anyone mention problems with convert on the mailing list recently, but there was a similar topic back in february.

Can you post the output of:

btrfs --version
uname -a

Also, what mount options are you using for this array?

pums974 · 2015-05-06 13:34:58

I just had an revelation, my / is on a subvolume so I'm realizing that I'm not balancing the whole filesystem...

So everything is normal, I'm just an idiot...

I will retry on the real / now and it should be ok

To answer your questions anyway :

btrfs --version
btrfs-progs v4.0

uname -a
Linux Grand-PC 4.0.1-1-ARCH #1 SMP PREEMPT Wed Apr 29 12:00:26 CEST 2015 x86_64 GNU/Linux

/dev/sda5 on / type btrfs (rw,relatime,thread_pool=9,compress=lzo,space_cache,autodefrag)

nstgc · 2015-05-06 14:16:38

It shouldn't matter that the target is the mount point for a subvolume, but yeah, you may want to mount the actual volume. Something like "# mount /dev/sda5 /mnt" then "# btrfs bal start -dconvert=raid10 -mconvert=raid10 /mnt".

pums974 · 2015-05-06 14:48:07

You are right, it didn't change anything.

But I found the explanation : it is a bug in the linux 4.0 kernel
http://unix.stackexchange.com/questions … a-to-raid1

I don't have time to patch the kernel right know, so I guess I will wait and try again later

WorMzy · 2015-05-06 16:11:34

If you don't have time to patch, a quick workaround would be to downgrade your kernel (+headers, +propriety drivers) to the 3.19 series.

Or install linux-ck, which is still on 3.19 due to other problems, and is what I'm using (which is probably why I had no problems).

nstgc · 2015-05-07 01:57:51

That sucks. Good to know though. Thank you.

Make sure you may your thread as solved if you are satisfied.

nstgc · 2015-06-11 20:38:17

Is this still broken in 4. 0.4-2? I'm trying to convert something from within the June 2015 image without luck. Or is it just not reporting it correctly?

firecat53 · 2015-06-11 20:45:54

It won't be fixed until the 4.1 kernel.

Scott

nstgc · 2015-06-11 20:53:02

Ah, thanks.

[edit] The fix actually appears in 4.0.6. I just converted a RAID 1 to a RAID 10.

Last edited by nstgc (2015-06-26 00:45:09)

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#1 2015-05-05 21:55:29

[SOLVED] Switching raid level in btrfs

#2 2015-05-05 22:32:32

Re: [SOLVED] Switching raid level in btrfs

#3 2015-05-05 22:33:22

Re: [SOLVED] Switching raid level in btrfs

#4 2015-05-06 07:06:17

Re: [SOLVED] Switching raid level in btrfs

#5 2015-05-06 11:32:28

Re: [SOLVED] Switching raid level in btrfs

#6 2015-05-06 12:25:38

Re: [SOLVED] Switching raid level in btrfs

#7 2015-05-06 13:22:15

Re: [SOLVED] Switching raid level in btrfs

#8 2015-05-06 13:34:58

Re: [SOLVED] Switching raid level in btrfs

#9 2015-05-06 14:16:38

Re: [SOLVED] Switching raid level in btrfs

#10 2015-05-06 14:48:07

Re: [SOLVED] Switching raid level in btrfs

#11 2015-05-06 16:11:34

Re: [SOLVED] Switching raid level in btrfs

#12 2015-05-07 01:57:51

Re: [SOLVED] Switching raid level in btrfs

#13 2015-06-11 20:38:17

Re: [SOLVED] Switching raid level in btrfs

#14 2015-06-11 20:45:54

Re: [SOLVED] Switching raid level in btrfs

#15 2015-06-11 20:53:02

Re: [SOLVED] Switching raid level in btrfs

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