On Sun, Feb 28, 2016 at 12:15:21AM +0100, Martin Steigerwald wrote:
> On Samstag, 27. Februar 2016 22:14:50 CET Marc Haber wrote:
> > I have again the issue of no space left on device while rebalancing
> > (with btrfs-tools 4.4.1 on kernel 4.4.2 on Debian unstable):
> >
> > mh@fan:~$ sudo btrfs balance start /mnt/fanbtr
> > ERROR: error during balancing '/mnt/fanbtr': No space left on device
> > mh@fan:~$ sudo btrfs fi show /mnt/fanbtr
> > mh@fan:~$ sudo btrfs fi show -m
> > Label: 'fanbtr' uuid: 4198d1bc-e3ce-40df-a7ee-44a2d120bff3
> > Total devices 1 FS bytes used 116.49GiB
> > devid 1 size 417.19GiB used 177.06GiB path /dev/mapper/fanbtr
>
> Hmmm, thats still a ton of space to allocate chunks from.
>
> > mh@fan:~$ sudo btrfs fi df /mnt/fanbtr
> > Data, single: total=113.00GiB, used=112.77GiB
> > System, DUP: total=32.00MiB, used=48.00KiB
> > Metadata, DUP: total=32.00GiB, used=3.72GiB
> > GlobalReserve, single: total=512.00MiB, used=0.00B
> > mh@fan:~$
> >
> > The filesystem was recently resized from 300 GB to 420 GB.
> >
> > Why does btrfs fi show /mnt/fanbtr not give any output? Wy does btrfs
> > fi df /mnt/fanbtr say that my data space is only 113 GiB large?
>
> Cause it is.
>
> The "used" in "devid 1" line is btrfs fi sh is "data + 2x system + 2x
> metadata
> = 113 GiB + 2 * 32 GiB + 2 * 32 MiB, i.e. what amount of the size of the
> device is allocated for chunks.
>
> The value one line above is what is allocated inside the chunks.
>
> I.e. the line in "devid 1" is "total" of btrfs fi df summed up, and the line
> above is "used" in btrfs fi df summed up. And… with more devices you have
> more
> fun.
Why wouldn't btrfs allocate more data chunks from the ample free space?
> I suggest:
>
> merkaba:~> btrfs fi usage -T /daten
[2/498]mh@fan:~$ sudo btrfs fi usage /mnt/fanbtr
Overall:
Device size: 417.19GiB
Device allocated: 177.06GiB
Device unallocated: 240.12GiB
Device missing: 0.00B
Used: 120.23GiB
Free (estimated): 240.33GiB (min: 120.27GiB)
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 512.00MiB (used: 0.00B)
Data,single: Size:113.00GiB, Used:112.79GiB
/dev/mapper/fanbtr 113.00GiB
Metadata,DUP: Size:32.00GiB, Used:3.72GiB
/dev/mapper/fanbtr 64.00GiB
System,DUP: Size:32.00MiB, Used:48.00KiB
/dev/mapper/fanbtr 64.00MiB
[3/498]mh@fan:~$ sudo btrfs fi usage -T /mnt/fanbtr
Overall:
Device size: 417.19GiB
Device allocated: 177.06GiB
Device unallocated: 240.12GiB
Device missing: 0.00B
Used: 120.23GiB
Free (estimated): 240.33GiB (min: 120.27GiB)
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 512.00MiB (used: 0.00B)
Data Metadata System
Id Path single DUP DUP Unallocated
-- ------------------ --------- -------- -------- -----------
1 /dev/mapper/fanbtr 113.00GiB 64.00GiB 64.00MiB 240.12GiB
-- ------------------ --------- -------- -------- -----------
Total 113.00GiB 32.00GiB 32.00MiB 240.12GiB
Used 112.79GiB 3.72GiB 48.00KiB
[4/499]mh@fan:~$
> (this is actually the situation asking for hung task trouble with kworker
> threads seeking for free space inside chunks, as no new chunks can be
> allocated, lets hope kernel 4.4 finally really has fixes for this)
I am running a 4.4.2 kernel on the system in question.
> Adding a new device temporarily, doing the balance and then removing it.
I currently refuse to do this on a 400 GiB device that has more than
half of its capacity free. I do expect a modern filesystem to get out
of that situation without a manual intervention this invasive.
> Before that I´d try to balance the metadata chunks, cause
>
> > Metadata, DUP: total=32.00GiB, used=3.72GiB
>
> 32 GiB chunks allocated, only 3,72 GiB used.
Why would I rebalance metadata if there is less than 20 % used?
[21/504]mh@fan:~$ sudo btrfs balance start -musage=5 /mnt/fanbtr
ERROR: error during balancing '/mnt/fanbtr': No space left on device
There may be more info in syslog - try dmesg | tail
[22/505]mh@fan:~$ sudo btrfs balance start -musage=1 /mnt/fanbtr
Done, had to relocate 56 out of 179 chunks
[23/506]mh@fan:~$ sudo btrfs balance start -musage=1 /mnt/fanbtr
Done, had to relocate 56 out of 179 chunks
[24/506]mh@fan:~$ sudo btrfs balance start -musage=1 /mnt/fanbtr
Done, had to relocate 56 out of 179 chunks
[25/506]mh@fan:~$ sudo btrfs balance start -musage=5 /mnt/fanbtr
Done, had to relocate 56 out of 179 chunks
[26/507]mh@fan:~$ sudo btrfs balance start -musage=50 /mnt/fanbtr
Done, had to relocate 56 out of 179 chunks
[27/508]mh@fan:~$ sudo btrfs balance start -musage=90 /mnt/fanbtr
Done, had to relocate 61 out of 179 chunks
[29/510]mh@fan:~$ sudo btrfs balance start -musage=90 /mnt/fanbtr
ERROR: error during balancing '/mnt/fanbtr': No space left on device
There may be more info in syslog - try dmesg | tail
[30/511]mh@fan:~$ sudo btrfs balance start -musage=90 /mnt/fanbtr
ERROR: error during balancing '/mnt/fanbtr': No space left on device
There may be more info in syslog - try dmesg | tail
[31/511]mh@fan:~$ sudo btrfs fi usage -T /mnt/fanbtr
Overall:
Device size: 417.19GiB
Device allocated: 177.06GiB
Device unallocated: 240.12GiB
Device missing: 0.00B
Used: 120.24GiB
Free (estimated): 240.32GiB (min: 120.26GiB)
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 512.00MiB (used: 0.00B)
Data Metadata System
Id Path single DUP DUP Unallocated
-- ------------------ --------- -------- -------- -----------
1 /dev/mapper/fanbtr 113.00GiB 64.00GiB 64.00MiB 240.12GiB
-- ------------------ --------- -------- -------- -----------
Total 113.00GiB 32.00GiB 32.00MiB 240.12GiB
Used 112.80GiB 3.72GiB 48.00KiB
[32/512]mh@fan:~$
Why does the number of reallocated chunks not decrease, why does
-musage=90 finish the first time and throw out of space errors on
subsequent invocations, and why doesn't the balance change anything in
btrfs fi usage?
> Maybe that way you can gain more free space to have a full balance run.
Why would i need more free space? there are 240 GiB free!
> Also note that it is not necessary to do a full balance in case everything
> works okayish.
The filesystem does not look healthy to me.
Greetings
Marc
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Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Leimen, Germany | lose things." Winona Ryder | Fon: *49 6224 1600402
Nordisch by Nature | How to make an American Quilt | Fax: *49 6224 1600421
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