Re: btrfs-transacti hammering the system

[Matt McKinnon <matt@techsquare.com>]

Well, it's at zero now...

# btrfs fi df /export/
Data, single: total=30.45TiB, used=30.25TiB
System, DUP: total=32.00MiB, used=3.62MiB
Metadata, DUP: total=66.50GiB, used=65.16GiB
GlobalReserve, single: total=512.00MiB, used=0.00B


On 01/12/17 16:47, Duncan wrote:
> Hans van Kranenburg posted on Fri, 01 Dec 2017 18:06:23 +0100 as
> excerpted:
> 
>> On 12/01/2017 05:31 PM, Matt McKinnon wrote:
>>> Sorry, I missed your in-line reply:
>>>
>>>
>>>> 2) How big is this filesystem? What does your `btrfs fi df
>>>> /mountpoint` say?
>>>>
>>>
>>> # btrfs fi df /export/
>>> Data, single: total=30.45TiB, used=30.25TiB
>>> System, DUP: total=32.00MiB, used=3.62MiB
>>> Metadata, DUP: total=66.50GiB, used=65.08GiB
>>> GlobalReserve, single: total=512.00MiB, used=53.69MiB
>>
>> Multi-TiB filesystem, check. total/used ratio looks healthy.
> 
> Not so healthy, from here.  Data/metadata are healthy, yes,
> but...
> 
> Any usage at all of global reserve is a red flag indicating that
> something in the filesystem thinks, or thought when it resorted
> to global reserve, that space is running out.
> 
> Global reserve usage doesn't really hint what the problem is,
> but it's definitely a red flag that there /is/ a problem, and
> it's easily overlooked, as it apparently was here.
> 
> It's likely indication of a bug, possibly one of the ones fixed
> right around 4.12/4.13.  I'll let the devs and better experts take
> it from there, but I'd certainly be worried until global reserve
> drops to zero usage.
>