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Subject: Re: your mail
To: linux-btrfs@vger.kernel.org
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From: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
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Date: Thu, 1 Sep 2016 07:17:38 -0400
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On 2016-09-01 03:44, M G Berberich wrote:
> Am Mittwoch, den 31. August schrieb Fennec Fox:
>> Linux Titanium 4.7.2-1-MANJARO #1 SMP PREEMPT Sun Aug 21 15:04:37 UTC
>> 2016 x86_64 GNU/Linux
>> btrfs-progs v4.7
>>
>> Data, single: total=30.01GiB, used=18.95GiB
>> System, single: total=4.00MiB, used=16.00KiB
>> Metadata, single: total=1.01GiB, used=422.17MiB
>> GlobalReserve, single: total=144.00MiB, used=0.00B
>>
>> {02:50} Wed Aug 31
>> [fennectech@Titanium ~]$  sudo fstrim -v /
>> [sudo] password for fennectech:
>> Sorry, try again.
>> [sudo] password for fennectech:
>> /: 99.8 GiB (107167244288 bytes) trimmed
>>
>> {03:08} Wed Aug 31
>> [fennectech@Titanium ~]$  sudo fstrim -v /
>> [sudo] password for fennectech:
>> /: 99.9 GiB (107262181376 bytes) trimmed
>>
>>   I ran these commands minutes after echother ane each time it is
>> trimming the entire free space
>>
>> Anyone else seen this?   the filesystem is the root FS and is compressed
>
> You should be very happy that it is trimming at all. Typical situation
> on a used btrfs is
>
>   # fstrim -v /
>   /: 0 B (0 bytes) trimmed
>
> even if there is 33G unused space ob the fs:
>
>   # df -h /
>   Filesystem      Size  Used Avail Use% Mounted on
>   /dev/sda2        96G   61G   33G  66% /
>
I think you're using an old kernel, this has been working since at least 
4.5, but was broken in some older releases.