* Change "small" filesystem to normal
@ 2012-07-22 15:06 Swâmi Petaramesh
2012-07-22 15:14 ` Ilya Dryomov
2012-07-22 15:37 ` Roman Mamedov
0 siblings, 2 replies; 6+ messages in thread
From: Swâmi Petaramesh @ 2012-07-22 15:06 UTC (permalink / raw)
To: linux-btrfs
Hi,
I've created a "small" BTRFS filesystem, where metadata+data are mixed
(and metadata are not DUP'ed).
Then I've enlarged the FS to 1 GB ; now I'd like to make it "normal"
with separate data and metadata, and "DUP'ed" metadata.
Is there a way tp do this without reformatting the FS ?
TIA, kind regards.
--
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Change "small" filesystem to normal
2012-07-22 15:06 Change "small" filesystem to normal Swâmi Petaramesh
@ 2012-07-22 15:14 ` Ilya Dryomov
2012-07-22 15:37 ` Roman Mamedov
1 sibling, 0 replies; 6+ messages in thread
From: Ilya Dryomov @ 2012-07-22 15:14 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: linux-btrfs
On Sun, Jul 22, 2012 at 05:06:24PM +0200, Swâmi Petaramesh wrote:
> Hi,
>
> I've created a "small" BTRFS filesystem, where metadata+data are mixed
> (and metadata are not DUP'ed).
>
> Then I've enlarged the FS to 1 GB ; now I'd like to make it "normal"
> with separate data and metadata, and "DUP'ed" metadata.
>
> Is there a way tp do this without reformatting the FS ?
No, currently there is no way to do this. You'll have to create a new
filesystem with mkfs.btrfs.
Thanks,
Ilya
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Change "small" filesystem to normal
2012-07-22 15:06 Change "small" filesystem to normal Swâmi Petaramesh
2012-07-22 15:14 ` Ilya Dryomov
@ 2012-07-22 15:37 ` Roman Mamedov
2012-07-23 4:55 ` Swâmi Petaramesh
1 sibling, 1 reply; 6+ messages in thread
From: Roman Mamedov @ 2012-07-22 15:37 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: linux-btrfs
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On Sun, 22 Jul 2012 17:06:24 +0200
Swâmi Petaramesh <swami@petaramesh.org> wrote:
> Hi,
>
> I've created a "small" BTRFS filesystem, where metadata+data are mixed
> (and metadata are not DUP'ed).
>
> Then I've enlarged the FS to 1 GB ; now I'd like to make it "normal"
> with separate data and metadata, and "DUP'ed" metadata.
Considering the metadata overallocation bug [1] is still not fixed even in the
latest kernels and no one seems to care all that much, I would not recommend
doing that.
Personally I now use a "mixed" filesystem on a 1TB disk without any problems,
and do not think there's anything wrong with "mixed". In fact there's been
some talk of moving to the mixed mode allocation to be used by default, and
maybe even removing support for the "split" mode: see [2].
[1] http://comments.gmane.org/gmane.comp.file-systems.btrfs/17848
[2] http://kerneltrap.org/mailarchive/linux-btrfs/2010/10/29/6885925
--
With respect,
Roman
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Change "small" filesystem to normal
2012-07-22 15:37 ` Roman Mamedov
@ 2012-07-23 4:55 ` Swâmi Petaramesh
2012-07-23 5:50 ` cwillu
0 siblings, 1 reply; 6+ messages in thread
From: Swâmi Petaramesh @ 2012-07-23 4:55 UTC (permalink / raw)
To: Roman Mamedov; +Cc: linux-btrfs
You're painfully right Roman,
A freshly formatted 1 GB BTRFS filesystem on which 81 MB of data has
been put shows only ~260 MB of free space and reserves something like 2
x 380 MB of metadata.
This is absolutely ridiculous of BTRFS... :-/
Kind regards.
Le 22/07/2012 17:37, Roman Mamedov a écrit :
> On Sun, 22 Jul 2012 17:06:24 +0200
> Swâmi Petaramesh <swami@petaramesh.org> wrote:
>
>> Hi,
>>
>> I've created a "small" BTRFS filesystem, where metadata+data are mixed
>> (and metadata are not DUP'ed).
>>
>> Then I've enlarged the FS to 1 GB ; now I'd like to make it "normal"
>> with separate data and metadata, and "DUP'ed" metadata.
> Considering the metadata overallocation bug [1] is still not fixed even in the
> latest kernels and no one seems to care all that much, I would not recommend
> doing that.
>
> Personally I now use a "mixed" filesystem on a 1TB disk without any problems,
> and do not think there's anything wrong with "mixed". In fact there's been
> some talk of moving to the mixed mode allocation to be used by default, and
> maybe even removing support for the "split" mode: see [2].
>
> [1] http://comments.gmane.org/gmane.comp.file-systems.btrfs/17848
>
> [2] http://kerneltrap.org/mailarchive/linux-btrfs/2010/10/29/6885925
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Change "small" filesystem to normal
2012-07-23 4:55 ` Swâmi Petaramesh
@ 2012-07-23 5:50 ` cwillu
2012-07-23 5:51 ` cwillu
0 siblings, 1 reply; 6+ messages in thread
From: cwillu @ 2012-07-23 5:50 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: Roman Mamedov, linux-btrfs
On Sun, Jul 22, 2012 at 10:55 PM, Swâmi Petaramesh <swami@petaramesh.org> wrote:
> You're painfully right Roman,
>
> A freshly formatted 1 GB BTRFS filesystem on which 81 MB of data has been
> put shows only ~260 MB of free space and reserves something like 2 x 380 MB
> of metadata.
>
> This is absolutely ridiculous of BTRFS... :-/
That's an artifact of the small size of that filesystem and the
default size of allocations, which is why mixed mode exists.
The metadata allocation is about 4% on most filesystems: I see 38gb of
allocated but unused metadata space on a 900gb fs and 70gb on a 1.7tb
fs, and the referenced threads reports 170gb on what appears to be a
4tb fs; while not ideal, it's not remotely as bad as the 25% overhead
of the minimum 256mb*2 metadata allocation on a small 1gb fs*. The
behaviour of a small filesystem simply isn't the same as the behaviour
of a large filesystem.
* Note that 1gb is still considered a very rather btrfs filesystem,
for which mixed mode is recommended!
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-07-23 5:51 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-07-22 15:06 Change "small" filesystem to normal Swâmi Petaramesh
2012-07-22 15:14 ` Ilya Dryomov
2012-07-22 15:37 ` Roman Mamedov
2012-07-23 4:55 ` Swâmi Petaramesh
2012-07-23 5:50 ` cwillu
2012-07-23 5:51 ` cwillu
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