Re: [RFC][PATCH] btrfs-progs: inspect: new subcommand to dump chunks
From: Hans van Kranenburg <hidden>
Date: 2016-06-23 01:10:16
On 06/22/2016 07:26 PM, David Sterba wrote:
From: David Sterba <redacted>
Hi,
the chunk dump is a useful thing, for debugging or balance filters.
Example output:
Chunks on device id: 1
PNumber Type PStart Length PEnd Age LStart Usage
-----------------------------------------------------------------------------------------------
0 System/RAID1 1.00MiB 32.00MiB 33.00MiB 47 1.40TiB 0.06
1 Metadata/RAID1 33.00MiB 1.00GiB 1.03GiB 31 1.36TiB 64.03
2 Metadata/RAID1 1.03GiB 32.00MiB 1.06GiB 36 1.36TiB 77.28
3 Data/single 1.06GiB 1.00GiB 2.06GiB 12 422.30GiB 78.90
4 Data/single 2.06GiB 1.00GiB 3.06GiB 11 420.30GiB 78.47
...
On RAID0, it looks funny :)
# ./btrfs inspect-internal dump-chunks /mnt/extents/
Chunks on device id: 1
PNumber Type PStart Length PEnd Age LStart
----------------------------------------------------------------------------------------
0 Metadata/RAID0 1.00MiB 256.00MiB 257.00MiB 1 13.36GiB
. empty . 16.00EiB . . .
1 System/RAID0 129.00MiB 64.00MiB 193.00MiB 2 13.61GiB
. empty . 16.00EiB . . .
2 Data/RAID0 161.00MiB 2.00GiB 2.16GiB 3 15.68GiB
. empty . 115.00MiB . . .
3 Data/RAID0 2.27GiB 2.00GiB 4.27GiB 0 11.36GiB
Chunks on device id: 2
PNumber Type PStart Length PEnd
Age LStart
----------------------------------------------------------------------------------------
0 Data/RAID0 1.00MiB 2.00GiB 2.00GiB 0 11.36GiB
. empty . 16.00EiB . . .
1 Metadata/RAID0 1.00GiB 256.00MiB 1.25GiB 1 13.36GiB
. empty . 16.00EiB . . .
2 System/RAID0 1.13GiB 64.00MiB 1.19GiB 2 13.61GiB
. empty . 16.00EiB . . .
3 Data/RAID0 1.16GiB 2.00GiB 3.16GiB 3 15.68GiB
For the correct sizes, it would be needed to either do some math, like
if RAID0 then divide by 2, but I guess this gets horrible really soon
with RAID5 etc... Or, if you want to print everything in the physical
order, why not just dump the device tree with DEV_EXTENT which has the
exact length on disk, and fill in the missing information using the
reference to the chunk they belong to?
https://github.com/knorrie/python-btrfs/commit/be85c2a0e2774909b532326e99e0c23ab8467263
Sorry, couldn't resist /:D\
--
Hans van Kranenburg - System / Network Engineer
T +31 (0)10 2760434 | hans.van.kranenburg@mendix.com | www.mendix.com