* btrfs fi df gives only the total size that is currently allocated
@ 2011-03-19 19:16 Gal Buki
2011-03-19 19:51 ` Calvin Walton
0 siblings, 1 reply; 2+ messages in thread
From: Gal Buki @ 2011-03-19 19:16 UTC (permalink / raw)
To: linux-btrfs
Hi
I made a test RAID 10 with several old disks with various sizes.
I copied some files (~800MB)
When using btrfs fi df /mountpoint I get
Data: total=1.00GB, used=800.00MB
When I copy another ~800MB I get a total size of 2GB.
This goes on and on until I hit the max size of the RAID.
e.g.
Data: total=5.00GB, used=4.97GB
Is there a way to see what the max size will be without having to fill
the RAID first?
Thanks,
Gal
P.S. df -h doesn't help either because of the different disk sizes.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: btrfs fi df gives only the total size that is currently allocated
2011-03-19 19:16 btrfs fi df gives only the total size that is currently allocated Gal Buki
@ 2011-03-19 19:51 ` Calvin Walton
0 siblings, 0 replies; 2+ messages in thread
From: Calvin Walton @ 2011-03-19 19:51 UTC (permalink / raw)
To: Gal Buki; +Cc: linux-btrfs
On Sat, 2011-03-19 at 21:16 +0200, Gal Buki wrote:
> Hi
>=20
> I made a test RAID 10 with several old disks with various sizes.
> I copied some files (~800MB)
> When using btrfs fi df /mountpoint I get
> Data: total=3D1.00GB, used=3D800.00MB
> When I copy another ~800MB I get a total size of 2GB.
>=20
> This goes on and on until I hit the max size of the RAID.
> e.g.
> Data: total=3D5.00GB, used=3D4.97GB
>=20
> Is there a way to see what the max size will be without having to fil=
l=20
> the RAID first?
As I understand it: the simple answer is, unfortunately, =E2=80=9Cno=E2=
=80=9D. Because
metadata and data chunks are allocated on demand depending on how you
use the space, the best you could do would be to make a guess based on
current allocation ratios.
That is something which is pretty hard to do manually though=E2=80=94
particularly in the case of differently-sized disks=E2=80=94so some sor=
t of
estimation tool could be useful. (But it would be just that: an
estimate, not an exact count.)
This will get worse once btrfs supports having data with different raid
levels on the same filesystem, because you=E2=80=99ll have different am=
ounts of
=E2=80=9Cavailable=E2=80=9D space depending on which raid type the data=
in question is
stored with.
--=20
Calvin Walton <calvin.walton@kepstin.ca>
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