time for "balance"

time for "balance"

[Helmut Hullen]

Hallo, linux-btrfs,

I'm working with btrfs for some days.

btrfs-progs-20101101, kernel 2.6.35.8 (both self compiled).

First step:

        mkfs.btrfs /dev/sdd1
        mount /dev/sdd1 /srv/MM

for a 2 TByte partition, worked well.

Copying about 1,5 TByte data to this partition worked well.

Second step:

        btrfs device add /dev/sdc1 /srv/MM
        btrfs filesystem balance /srv/MM

adds /dev/sdc1 with about 1,5 TByte ("df" tells so), and the system  
works the second line ("balance") since about 12 hours. How much time  
needs this "balance" command?

If the machine hangs somewhere and I have to restart it: how can/must I  
repair the btrfs system?

Viele Gruesse!
Helmut

Re: time for "balance"

[Hugo Mills]

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B1;2401;0cOn Tue, Nov 09, 2010 at 04:09:00PM +0100, Helmut Hullen wrote:
>         btrfs device add /dev/sdc1 /srv/MM
>         btrfs filesystem balance /srv/MM
> 
> adds /dev/sdc1 with about 1,5 TByte ("df" tells so), and the system  
> works the second line ("balance") since about 12 hours. How much time  
> needs this "balance" command?

   Enough time to rewrite every piece of data in the filesystem.

   There are patches [1,2] for the kernel and userspace tools to allow
you to monitor the progress of a balance. I'll be putting out a new
revision of them either tonight or tomorrow (depending on how awkward
git is feeling).

[1] http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg06558.html
[2] http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg06561.html

> If the machine hangs somewhere and I have to restart it: how can/must I  
> repair the btrfs system?

   No need. Even while the balance is running, the filesystem should
remain in a consistent state (assuming that you have working
barriers). Note that if you restart the balance process, it will
effectively start from the beginning again.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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Re: time for "balance"

[Helmut Hullen]

Hallo,

I wrote am 09.11.10:

> I'm working with btrfs for some days.

> btrfs-progs-20101101, kernel 2.6.35.8 (both self compiled).

> First step:

>         mkfs.btrfs /dev/sdd1
>         mount /dev/sdd1 /srv/MM

> for a 2 TByte partition, worked well.

> Copying about 1,5 TByte data to this partition worked well.

> Second step:

>         btrfs device add /dev/sdc1 /srv/MM
>         btrfs filesystem balance /srv/MM

> adds /dev/sdc1 with about 1,5 TByte ("df" tells so), and the system
> works the second line ("balance") since about 12 hours. How much time
> needs this "balance" command?

Now the machine is ready, after working about 2 days ...

Viele Gruesse!
Helmut