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From: Duncan <1i5t5.duncan@cox.net>
Subject: Re: btrfs-transacti hammering the system
Date: Mon, 4 Dec 2017 14:10:05 +0000 (UTC)
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Austin S. Hemmelgarn posted on Mon, 04 Dec 2017 07:18:11 -0500 as
excerpted:

> On 2017-12-01 16:50, Matt McKinnon wrote:
>> 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

> GlobalReserve seems to be used temporarily for certain cases of metadata
> COW regardless of how full the FS actually is, I'm betting that it just so
> happened that such a case was in progress when you got the info
> previously.  If you aren't seeing it regularly used, it's (probably) not
> an issue.
> 
> Duncan is correct though when dealing with long-term usage.  If you see
> GlobalReserve usage that persists for an extended period of time,
> something is almost certainly wrong, especially if the FS isn't close to
> being full.

Thanks.  I wasn't aware global reserve was routinely temporarily used.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman