What's the minimum size I can shrink my FS to?

What's the minimum size I can shrink my FS to?

[Jordan Windsor]

Hello,
I'm trying to shrink my Btrfs filesystem to the smallest size it can
go, here's the information:

failed to read /dev/sr0
Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
Total devices 1 FS bytes used 491.86GB
devid    1 size 612.04GB used 605.98GB path /dev/sda6

Btrfs Btrfs v0.19

Data: total=580.90GB, used=490.88GB
System, DUP: total=32.00MB, used=76.00KB
System: total=4.00MB, used=0.00
Metadata, DUP: total=12.51GB, used=1001.61MB

Here's the command I use to resize:

[root@archpc ~]# btrfs file res 500g /home/jordan/Storage/
Resize '/home/jordan/Storage/' of '500g'
ERROR: unable to resize '/home/jordan/Storage/' - No space left on device

I was wondering if that size doesn't work then what's the minimum I
can shrink to?

Thanks.

Re: What's the minimum size I can shrink my FS to?

[cwillu]

Run "btrfs balance start -musage=1 -dusage=1", and then try it again.
This may require update btrfs tools however.

On Fri, Nov 2, 2012 at 10:09 PM, Jordan Windsor <jordanw2@gmail.com> wrote:
> Hello,
> I'm trying to shrink my Btrfs filesystem to the smallest size it can
> go, here's the information:
>
> failed to read /dev/sr0
> Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
> Total devices 1 FS bytes used 491.86GB
> devid    1 size 612.04GB used 605.98GB path /dev/sda6
>
> Btrfs Btrfs v0.19
>
> Data: total=580.90GB, used=490.88GB
> System, DUP: total=32.00MB, used=76.00KB
> System: total=4.00MB, used=0.00
> Metadata, DUP: total=12.51GB, used=1001.61MB
>
> Here's the command I use to resize:
>
> [root@archpc ~]# btrfs file res 500g /home/jordan/Storage/
> Resize '/home/jordan/Storage/' of '500g'
> ERROR: unable to resize '/home/jordan/Storage/' - No space left on device
>
> I was wondering if that size doesn't work then what's the minimum I
> can shrink to?
>
> Thanks.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: What's the minimum size I can shrink my FS to?

[Jordan Windsor]

Hello,
here's the new output:

[root@archpc ~]# btrfs bal start -musage=1 -dusage=1 /home/jordan/Storage/
Done, had to relocate 3 out of 609 chunks

[root@archpc ~]# btrfs fi df /home/jordan/Storage/
Data: total=580.88GB, used=490.88GB
System, DUP: total=32.00MB, used=76.00KB
System: total=4.00MB, used=0.00
Metadata, DUP: total=13.01GB, used=1001.83MB

[root@archpc ~]# btrfs fi sh
failed to read /dev/sr0
Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
Total devices 1 FS bytes used 491.86GB
devid    1 size 612.04GB used 606.96GB path /dev/sda6

Btrfs Btrfs v0.19

[root@archpc ~]# btrfs file res 500g /home/jordan/Storage/
Resize '/home/jordan/Storage/' of '500g'
ERROR: unable to resize '/home/jordan/Storage/' - No space left on device

Thanks.

(Had to resend forgot to CC the mailing list, sorry)

On Sat, Nov 3, 2012 at 3:09 PM, Jordan Windsor <jordanw2@gmail.com> wrote:
> Hello,
> here's the new output:
>
> [root@archpc ~]# btrfs bal start -musage=1 -dusage=1 /home/jordan/Storage/
> Done, had to relocate 3 out of 609 chunks
>
> [root@archpc ~]# btrfs fi df /home/jordan/Storage/
> Data: total=580.88GB, used=490.88GB
> System, DUP: total=32.00MB, used=76.00KB
> System: total=4.00MB, used=0.00
> Metadata, DUP: total=13.01GB, used=1001.83MB
>
> [root@archpc ~]# btrfs fi sh
> failed to read /dev/sr0
> Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
> Total devices 1 FS bytes used 491.86GB
> devid    1 size 612.04GB used 606.96GB path /dev/sda6
>
> Btrfs Btrfs v0.19
>
> [root@archpc ~]# btrfs file res 500g /home/jordan/Storage/
> Resize '/home/jordan/Storage/' of '500g'
> ERROR: unable to resize '/home/jordan/Storage/' - No space left on device
>
> Thanks.
>
> On Sat, Nov 3, 2012 at 2:43 PM, cwillu <cwillu@cwillu.com> wrote:
>> Run "btrfs balance start -musage=1 -dusage=1", and then try it again.
>> This may require update btrfs tools however.
>>
>> On Fri, Nov 2, 2012 at 10:09 PM, Jordan Windsor <jordanw2@gmail.com> wrote:
>>> Hello,
>>> I'm trying to shrink my Btrfs filesystem to the smallest size it can
>>> go, here's the information:
>>>
>>> failed to read /dev/sr0
>>> Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
>>> Total devices 1 FS bytes used 491.86GB
>>> devid    1 size 612.04GB used 605.98GB path /dev/sda6
>>>
>>> Btrfs Btrfs v0.19
>>>
>>> Data: total=580.90GB, used=490.88GB
>>> System, DUP: total=32.00MB, used=76.00KB
>>> System: total=4.00MB, used=0.00
>>> Metadata, DUP: total=12.51GB, used=1001.61MB
>>>
>>> Here's the command I use to resize:
>>>
>>> [root@archpc ~]# btrfs file res 500g /home/jordan/Storage/
>>> Resize '/home/jordan/Storage/' of '500g'
>>> ERROR: unable to resize '/home/jordan/Storage/' - No space left on device
>>>
>>> I was wondering if that size doesn't work then what's the minimum I
>>> can shrink to?
>>>
>>> Thanks.
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: What's the minimum size I can shrink my FS to?

[David Sterba]

On Sat, Nov 03, 2012 at 03:10:52PM +1030, Jordan Windsor wrote:
> [root@archpc ~]# btrfs fi df /home/jordan/Storage/
> Data: total=580.88GB, used=490.88GB

This is getting full, 84%, there is not much chance of getting rid of
substantially many 1G-chunks through the 'usage=1' balance filter.
Some of the space between 490G and 580G will be spent on slack space and
fragmentation, the rest may be packed together by a higher usage= value
(but will be slower due to relocating more data).

> System, DUP: total=32.00MB, used=76.00KB
> System: total=4.00MB, used=0.00
> Metadata, DUP: total=13.01GB, used=1001.83MB

If you intend to shrink a filesystem, all space group types must be
taken into account, so here you have at least

580G + 2x32M + 4M + 2x13G = ~607G

> [root@archpc ~]# btrfs fi sh
> failed to read /dev/sr0
> Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
> Total devices 1 FS bytes used 491.86GB
> devid    1 size 612.04GB used 606.96GB path /dev/sda6
                                ^^^^^^
confirmed :)

So basically you cannot go under this number when shrinking. I think you
can squeeze the metadata space down to 2G (or maybe to 1G, it's getting
very close to 1G so hard to guess) by the -musage= filter AND using at
least 3.7 kernel (or 3.6+ chris' for-linus branch) with the fixed
over-allocation bug (otherwise the size will stay pinned at 2% of the
filesystem size).

david

Re: What's the minimum size I can shrink my FS to?

[Jordan Windsor]

On Tue, Nov 6, 2012 at 9:45 AM, David Sterba <dave@jikos.cz> wrote:
> On Sat, Nov 03, 2012 at 03:10:52PM +1030, Jordan Windsor wrote:
>> [root@archpc ~]# btrfs fi df /home/jordan/Storage/
>> Data: total=580.88GB, used=490.88GB
>
> This is getting full, 84%, there is not much chance of getting rid of
> substantially many 1G-chunks through the 'usage=1' balance filter.
> Some of the space between 490G and 580G will be spent on slack space and
> fragmentation, the rest may be packed together by a higher usage= value
> (but will be slower due to relocating more data).
>
>> System, DUP: total=32.00MB, used=76.00KB
>> System: total=4.00MB, used=0.00
>> Metadata, DUP: total=13.01GB, used=1001.83MB
>
> If you intend to shrink a filesystem, all space group types must be
> taken into account, so here you have at least
>
> 580G + 2x32M + 4M + 2x13G = ~607G
>
>> [root@archpc ~]# btrfs fi sh
>> failed to read /dev/sr0
>> Label: 'Storage'  uuid: 717d4a43-38b3-495f-841b-d223068584de
>> Total devices 1 FS bytes used 491.86GB
>> devid    1 size 612.04GB used 606.96GB path /dev/sda6
>                                 ^^^^^^
> confirmed :)
>
> So basically you cannot go under this number when shrinking. I think you
> can squeeze the metadata space down to 2G (or maybe to 1G, it's getting
> very close to 1G so hard to guess) by the -musage= filter AND using at
> least 3.7 kernel (or 3.6+ chris' for-linus branch) with the fixed
> over-allocation bug (otherwise the size will stay pinned at 2% of the
> filesystem size).
>
> david

Thanks for the info! Shame I can't save space though.
Thanks anyway.