* Shrinking virtual disk with btrfs on it
@ 2011-01-21 17:20 Rodney Beede
2011-01-21 17:34 ` Hugo Mills
2011-01-21 19:43 ` David Pottage
0 siblings, 2 replies; 5+ messages in thread
From: Rodney Beede @ 2011-01-21 17:20 UTC (permalink / raw)
To: linux-btrfs
Any tools to go about zeroing about the free space on a btrfs file
system so I can shrink the VMware vmdk virtual disk?
I ran the VMware command, but the dynamic disk is still really big. I
presume it is due to free space that isn't zeroed out.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Shrinking virtual disk with btrfs on it
2011-01-21 17:20 Shrinking virtual disk with btrfs on it Rodney Beede
@ 2011-01-21 17:34 ` Hugo Mills
2011-01-22 18:27 ` Rodney Beede
2011-01-21 19:43 ` David Pottage
1 sibling, 1 reply; 5+ messages in thread
From: Hugo Mills @ 2011-01-21 17:34 UTC (permalink / raw)
To: Rodney Beede; +Cc: linux-btrfs
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On Fri, Jan 21, 2011 at 10:20:34AM -0700, Rodney Beede wrote:
> Any tools to go about zeroing about the free space on a btrfs file
> system so I can shrink the VMware vmdk virtual disk?
>
> I ran the VMware command, but the dynamic disk is still really big. I
> presume it is due to free space that isn't zeroed out.
One solution I've used before is to write a single very large file
full of zeroes, filling the filesystem, then delete it.
$ dd if=/dev/zero of=/mountpoint/foo.dat && rm /mountpoint/foo.dat
Hugo.
--
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
--- ... one ping(1) to rule them all, and in the ---
darkness bind(2) them.
[-- Attachment #2: Digital signature --]
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Shrinking virtual disk with btrfs on it
2011-01-21 17:20 Shrinking virtual disk with btrfs on it Rodney Beede
2011-01-21 17:34 ` Hugo Mills
@ 2011-01-21 19:43 ` David Pottage
2011-01-22 8:28 ` Tomasz Torcz
1 sibling, 1 reply; 5+ messages in thread
From: David Pottage @ 2011-01-21 19:43 UTC (permalink / raw)
To: Rodney Beede, linux-btrfs
On 21/01/11 17:20, Rodney Beede wrote:
> Any tools to go about zeroing about the free space on a btrfs file
> system so I can shrink the VMware vmdk virtual disk?
>
> I ran the VMware command, but the dynamic disk is still really big. I
> presume it is due to free space that isn't zeroed out.
Does btrfs issue TRIM commands to the underlying (virtual) block device?
I guess not yet, as otherwise you would not see this problem, as your
virtual storage device should catch them and discard the corresponding
virtual storage blocks.
--
David Pottage
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Shrinking virtual disk with btrfs on it
2011-01-21 19:43 ` David Pottage
@ 2011-01-22 8:28 ` Tomasz Torcz
0 siblings, 0 replies; 5+ messages in thread
From: Tomasz Torcz @ 2011-01-22 8:28 UTC (permalink / raw)
To: linux-btrfs
On Fri, Jan 21, 2011 at 07:43:47PM +0000, David Pottage wrote:
> On 21/01/11 17:20, Rodney Beede wrote:
> > Any tools to go about zeroing about the free space on a btrfs file
> > system so I can shrink the VMware vmdk virtual disk?
> >
> > I ran the VMware command, but the dynamic disk is still really big. I
> > presume it is due to free space that isn't zeroed out.
> Does btrfs issue TRIM commands to the underlying (virtual) block device?
It does when mounted with - o discard. IIRC, btrfs also supports
FITRIM ioctl (but I'm not 100% sure about this).
--
Tomasz Torcz RIP is irrevelant. Spoofing is futile.
xmpp: zdzichubg@chrome.pl Your routes will be aggreggated. -- Alex Yuriev
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Shrinking virtual disk with btrfs on it
2011-01-21 17:34 ` Hugo Mills
@ 2011-01-22 18:27 ` Rodney Beede
0 siblings, 0 replies; 5+ messages in thread
From: Rodney Beede @ 2011-01-22 18:27 UTC (permalink / raw)
To: linux-btrfs
On Fri, Jan 21, 2011 at 10:34 AM, Hugo Mills <hugo-lkml@carfax.org.uk> =
wrote:
> On Fri, Jan 21, 2011 at 10:20:34AM -0700, Rodney Beede wrote:
>> Any tools to go about zeroing about the free space on a btrfs file
>> system so I can shrink the VMware vmdk virtual disk?
>>
>> I ran the VMware command, but the dynamic disk is still really big. =
=C2=A0I
>> presume it is due to free space that isn't zeroed out.
>
> =C2=A0 One solution I've used before is to write a single very large =
file
> full of zeroes, filling the filesystem, then delete it.
>
> $ dd if=3D/dev/zero of=3D/mountpoint/foo.dat && rm /mountpoint/foo.da=
t
>
> =C2=A0 Hugo.
>
> --
> =3D=3D=3D Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.=
org.uk =3D=3D=3D
> =C2=A0PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.=
org.uk
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0--- ... =C2=A0one ping(1) to rule t=
hem all, and in the ---
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
=C2=A0 =C2=A0 darkness bind(2) them.
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.10 (GNU/Linux)
>
> iD8DBQFNOcObIKyzvlFcI40RAodJAJ0VyXnvxNH2MxTZ08uT8WaywsA=ED=88=80=E9=BD=
=82=E4=95=BA
> 7MRCSpCsPWGiXeS73ItqnWA=3D
> =3Dngld
> -----END PGP SIGNATURE-----
>
>
I tried your method, and it made things worst. The disk just expanded
to the maximum. I deleted the zero filled file and made sure btrfs
compress was off. I ran the VMware disk manage tool and told it to
defragment and shrink but it didn't get any smaller. I think btrfs
just doesn't work that way.
I also tried btrfs filesystem defragment with no luck.
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2011-01-21 17:20 Shrinking virtual disk with btrfs on it Rodney Beede
2011-01-21 17:34 ` Hugo Mills
2011-01-22 18:27 ` Rodney Beede
2011-01-21 19:43 ` David Pottage
2011-01-22 8:28 ` Tomasz Torcz
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