On 06/02/2013 06:28 PM, Liu Bo wrote:
On Sun, Jun 02, 2013 at 07:40:52AM -0700, George Mitchell wrote:
I am seeing massive journal corruptions that seem to be unique to
btrfs and I am suspecting that cow might be causing them. My
bandaid fix for this will be to mark the /var filesystem "nodatacow"
at boot. But I am wondering if their is any way to flag a
particular directory as "nodatacow" outside of the mount process. I
would like to be able to mark /var/log/journal as "nodatacow" for
example, without having to declare it a subvolume and mount it
separately.
Hi George,
We actually have per-file/directory nodatacow :)
But please note if you set nodatacow on the particular directory, only
new-created or zero-size files in the directory can follow the nocow rule.
'chattr' in the latest e2fsprogs can fit your requirements,
# chattr +C /var/log/journal
Also, what kind of massive journal corruptions? Does it look like a
btrfs specific bug?
thanks,
liubo
Thanks Liu,
That helps a lot! I am very familiar with chattr/lsattr from my ext3
days, but didn't know where to look for btrfs options. From what you are
telling me the nodatacow option is identical to nodatacow option for
ext3. Do the other ext3 options work for btrfs also?
As for as the corruption issue, I actually don't know whether the
corruptions are real or whether they are being caused by the way the
`journalctl --verify` command is interfacing with the filesystem. My
suspicion is that metadata fragmentation *might* be somehow messing with
the `journalctl --verify` since I can use simply `journalctl` and all
the data flows out without error. I just cleaned out the
/var/log/journal directory and started fresh and in no time I am seeing
corruptions according to `journalctl --verify`. Here is what the output
looks like:
==============================================================================
[root@localhost aide]# journalctl --verify
Invalid object contents at
130624░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000628-0004de2c1807989c.journal:130624
(of 131072, 99%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000628-0004de2c1807989c.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000065a-0004de2c18d6d96d.journal
Invalid object contents at
125264░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000069a-0004de2c5e323847.journal:125264
(of 131072, 95%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000069a-0004de2c5e323847.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-00000000000006a8-0004de2c73b5f19d.journal
Invalid object contents at
128408░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000709-0004de2cedab583c.journal:128408
(of 131072, 97%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000709-0004de2cedab583c.journal
(Bad message)
Invalid object contents at
126736░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000077f-0004de2d20abe261.journal:126736
(of 131072, 96%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000077f-0004de2d20abe261.journal
(Bad message)
Invalid object contents at
129600░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000007ec-0004de2d7c50c186.journal:129600
(of 131072, 98%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000007ec-0004de2d7c50c186.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-00000000000007f1-0004de2d87392b08.journal
Invalid object contents at
129256░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000862-0004de2e9a6decf4.journal:129256
(of 131072, 98%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000862-0004de2e9a6decf4.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000087d-0004de2eaee97998.journal
Invalid object contents at
126032░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000008de-0004de2fb88c29cb.journal:126032
(of 131072, 96%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000008de-0004de2fb88c29cb.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000947-0004de30cc6f8833.journal
Invalid object contents at
130952░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000957-0004de30d6aad93f.journal:130952
(of 131072, 99%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000957-0004de30d6aad93f.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000098b-0004de31213bbbae.journal
Invalid object contents at
124168░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000009d1-0004de31f4c7533d.journal:124168
(of 131072, 94%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000009d1-0004de31f4c7533d.journal
(Bad message)
Invalid object contents at
130784░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000a47-0004de3312e5e75d.journal:130784
(of 131072, 99%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000a47-0004de3312e5e75d.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000a8d-0004de33b65f55f2.journal
Invalid object contents at
129744░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000abb-0004de33e97b96d8.journal:129744
(of 131072, 98%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000abb-0004de33e97b96d8.journal
(Bad message)
PASS:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000ad1-0004de341fd95f50.journal
Invalid object contents at
129864░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
0%
File corruption detected at
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000b37-0004de34e40af053.journal:129864
(of 131072, 99%).
FAIL:
/var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000b37-0004de34e40af053.journal
(Bad message)
PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system.journal
==============================================================================
So I want to try forcing "nodatacow" on this directory and see what
happens. If that doesn't work, I suppose the next step will be to place
this one directory on an ext4 filesystem and mount it externally to the
btrfs /var/log. What I do know is that I have a parallel maintenance
system on the same hardware using ext4 and it has never had a problem
like this. I have also had a boot problem from the beginning and that
seems like it got fixed by doing rigorous defragmentation on the btrfs
root filesystem. So I really don't know at this point what is causing
this problem, but I am determined to do my best to find out. The system
I am having the problem with has been running Mageia 3 100% on btrfs
RAID 1 migrated from Mageia 2 100% on 3ware hardware RAID 1. Making this
transition has been a quite an experience, but the system is up and
running fine. This is my day to day production system and since btrfs is
where it is right now, this system is rigorously backed up every three
hours to a JFS formatted drive and daily to a 4TB btrfs formatted drive.
The system is also on UPS, but has actually hard crashed multiple times
early on without any resulting data corruption. But only by using btrfs
on a production system can I shag out all of these peripheral issues. So
thanks so much for the tip, it will get me one step further along in
sorting this out.
Sincerely,
George
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