Re: how to understand "btrfs fi show" output? "No space left" issues

[Tomasz Chmielewski <mangoo@wpkg.org>]

Yes, have it disabled already (for their datadirs).


Tomasz Chmielewski
https://lxadm.com


On 2016-09-20 16:30, Peter Becker wrote:
> for the future. disable COW for all database containers
> 
> 2016-09-20 9:28 GMT+02:00 Peter Becker <floyd.net@gmail.com>:
>> * If this NOT solve the "No space left" issues you must remove old 
>> snapshots.
>> 
>> 2016-09-20 9:27 GMT+02:00 Peter Becker <floyd.net@gmail.com>:
>>> Data, RAID1: total=417.12GiB, used=131.33GiB
>>> 
>>> You have 417(total)-131(used) blocks wo are only partial filled.
>>> You should balance your file-system.
>>> 
>>> At first you need some free space. You could remove some files / old
>>> snapshots etc. or you add a empty USB-Stick with min. 4 GB to your
>>> BTRFS-Pool (after balancing complete you can remove the stick from 
>>> the
>>> pool).
>>> 
>>> But at first you should try to free emty data and meta data blocks:
>>> 
>>> btrfs balance start -musage=0 /mnt
>>> btrfs balance start -dusage=0 /mnt
>>> 
>>> Then you an run a full balance or a partial balance:
>>> 
>>> #a partial balance with reorganize data blocks less then 50% filled
>>> btrfs balance start -dusage=50 /mnt
>>> 
>>> #or a full balance
>>> btrfs balance start /mnt
>>> 
>>> Because of a possible bug you should disable all snapshot scripts
>>> (like cron-jobs) during the balance.
>>> 
>>> If this solve the "No space left" issues you must remove old 
>>> snapshots.
>>> 
>>> 2016-09-20 8:58 GMT+02:00 Hugo Mills <hugo@carfax.org.uk>:
>>>> On Tue, Sep 20, 2016 at 03:47:14PM +0900, Tomasz Chmielewski wrote:
>>>>> How to understand the following "btrfs fi show" output?
>>>> 
>>>> This gives a write-up (and worked example) of an answer to your 
>>>> question:
>>>> 
>>>> https://btrfs.wiki.kernel.org/index.php/FAQ#Understanding_free_space.2C_using_the_original_tools
>>>> 
>>>>    If you've got any follow-up questions after reading it, please do
>>>> come back and we can try to improve the FAQ entry. :)
>>>> 
>>>>    Hugo.
>>>> 
>>>>> # btrfs fi show /var/lib/lxd
>>>>> Label: 'btrfs'  uuid: f5f30428-ec5b-4497-82de-6e20065e6f61
>>>>>         Total devices 2 FS bytes used 136.18GiB
>>>>>         devid    1 size 423.13GiB used 423.13GiB path /dev/sda3
>>>>>         devid    2 size 423.13GiB used 423.13GiB path /dev/sdb3
>>>>> 
>>>>> Why is it "size 423.13GiB used 423.13GiB"? Is it full?
>>>>> 
>>>>> I had "No space left" on this filesystem just yesterday (running
>>>>> kernel 4.7.4). This is btrfs RAID-1 on SSD disks. This filesystem 
>>>>> is
>>>>> used for 20-30 LXD containers with different roles (mongo, mysql,
>>>>> postgres databases, webservers etc.), around 150 read-only
>>>>> snapshots, btrfs compression is disabled.
>>>>> 
>>>>> 
>>>>> Both "btrfs fi df" and "df -h" show plenty of space:
>>>>> 
>>>>> # btrfs fi df /var/lib/lxd
>>>>> Data, RAID1: total=417.12GiB, used=131.33GiB
>>>>> System, RAID1: total=8.00MiB, used=80.00KiB
>>>>> Metadata, RAID1: total=6.00GiB, used=4.86GiB
>>>>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>>>> 
>>>>> 
>>>>> # df -h
>>>>> Filesystem      Size  Used Avail Use% Mounted on
>>>>> /dev/sda3       424G  137G  286G  33% /var/lib/lxd
>>>>> 
>>>>> 
>>>>> 
>>>>> Tomasz Chmielewski
>>>>> https://lxadm.com
>>>>> --
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>>>> 
>>>> --
>>>> Hugo Mills             | I can resist everything except temptation.
>>>> hugo@... carfax.org.uk |
>>>> http://carfax.org.uk/  |
>>>> PGP: E2AB1DE4          |