From: Martin Steigerwald <martin@lichtvoll.de>
To: linux-btrfs@vger.kernel.org
Subject: Understanding "Used" in df
Date: Wed, 22 Jul 2020 17:10:19 +0200 [thread overview]
Message-ID: <3225288.0drLW0cIUP@merkaba> (raw)
I have:
% LANG=en df -hT /home
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/sata-home btrfs 300G 175G 123G 59% /home
And:
merkaba:~> btrfs fi sh /home
Label: 'home' uuid: […]
Total devices 2 FS bytes used 173.91GiB
devid 1 size 300.00GiB used 223.03GiB path /dev/mapper/sata-home
devid 2 size 300.00GiB used 223.03GiB path /dev/mapper/msata-home
merkaba:~> btrfs fi df /home
Data, RAID1: total=218.00GiB, used=171.98GiB
System, RAID1: total=32.00MiB, used=64.00KiB
Metadata, RAID1: total=5.00GiB, used=1.94GiB
GlobalReserve, single: total=490.48MiB, used=0.00B
As well as:
merkaba:~> btrfs fi usage -T /home
Overall:
Device size: 600.00GiB
Device allocated: 446.06GiB
Device unallocated: 153.94GiB
Device missing: 0.00B
Used: 347.82GiB
Free (estimated): 123.00GiB (min: 123.00GiB)
Data ratio: 2.00
Metadata ratio: 2.00
Global reserve: 490.45MiB (used: 0.00B)
Multiple profiles: no
Data Metadata System
Id Path RAID1 RAID1 RAID1 Unallocated
-- ---------------------- --------- -------- -------- -----------
1 /dev/mapper/sata-home 218.00GiB 5.00GiB 32.00MiB 76.97GiB
2 /dev/mapper/msata-home 218.00GiB 5.00GiB 32.00MiB 76.97GiB
-- ---------------------- --------- -------- -------- -----------
Total 218.00GiB 5.00GiB 32.00MiB 153.94GiB
Used 171.97GiB 1.94GiB 64.00KiB
I think I understand all of it, including just 123G instead of
300 - 175 = 125 GiB "Avail" in df -hT.
But why 175 GiB "Used" in 'df -hT' when just 173.91GiB (see 'btrfs fi sh')
is allocated *within* the block group / chunks?
Does this have something to do with that global reserve thing?
Thank you,
--
Martin
next reply other threads:[~2020-07-22 15:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 15:10 Martin Steigerwald [this message]
2020-07-22 19:07 ` Understanding "Used" in df A L
2020-07-23 4:51 ` Zygo Blaxell
2020-07-27 11:38 ` Martin Steigerwald
2020-07-27 16:42 ` Andrei Borzenkov
2020-07-27 19:30 ` Chris Murphy
2020-07-27 19:48 ` Andrei Borzenkov
2020-07-27 20:47 ` Hugo Mills
2020-07-28 21:20 ` Zygo Blaxell
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