Ext4 errror?

fedora fedora at ayni.com
Mon Jul 5 14:24:06 UTC 2010


Hi listers

i got file system errors on a new machine (hw errors should therefore 
not be an issue, also smartctl does not indicate any errors), which 
holds two disks on SATA controllers. Both disks contain a fully fleged 
Fedora 13, so that i can boot from either of them.

i usually boot from the first disk, and i take care not to cross-mount 
the second disk or to unmount cross-mounts before hibernating.

[root at myws ~]# uname -a
Linux myws.lan 2.6.33.5-124.fc13.x86_64 #1 SMP Fri Jun 11 09:38:12 UTC 
2010 x86_64 x86_64 x86_64 GNU/Linux
[root at myws ~]#

The complete log of a boot cycle follows in the next message.

The file systems error manifests itself as follows in /var/log/messages:


Jul  5 07:04:59 myws kernel: EXT4-fs error (device dm-0): 
ext4_free_inode: bit already cleared for inode 136802
Jul  5 07:04:59 myws kernel: EXT4-fs error (device dm-0): 
ext4_free_inode: bit already cleared for inode 136803


When this error occurs i can no longer do such simple things as

touch /tmp/abcd.txt

which at this time gives me "No such file or directory"

to shut down the system, i usually use the hibernate function (i.e. save 
to the swap space), i mostly do not reboot the system. But then, after 
some resume/thaw cycles from the swap space, the above error happens, 
and i have to reboot.

when rebooting, the system goes through one ore two fsck cycles whith 
"File System has been modified, reboot needed" and reboots itself.

when the system comes up after that, the above error does not happen 
anymore, but i am not sure, whether the system is in the same state as 
before, i.e. i am not sure, whether i have lost data.

for /dev/sda (i.e. the first disk), the setup is as follows:

[root at myws ~]# fdisk -l /dev/sda

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00080a55

    Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26       60802   488180736   8e  Linux LVM
[root at myws ~]#

[root at myws ~]# pvdisplay
   --- Physical volume ---
   PV Name               /dev/sda2
   VG Name               vg_myws1
   PV Size               465.57 GiB / not usable 3.00 MiB
   Allocatable           yes (but full)
   PE Size               4.00 MiB
   Total PE              119184
   Free PE               0
   Allocated PE          119184
   PV UUID               GBw4su-TmW4-rLPj-v9fC-efEy-28jw-T4TGIj

[root at myws ~]#

[root at myws ~]# vgdisplay
   --- Volume group ---
   VG Name               vg_myws1
   System ID
   Format                lvm2
   Metadata Areas        1
   Metadata Sequence No  4
   VG Access             read/write
   VG Status             resizable
   MAX LV                0
   Cur LV                3
   Open LV               3
   Max PV                0
   Cur PV                1
   Act PV                1
   VG Size               465.56 GiB
   PE Size               4.00 MiB
   Total PE              119184
   Alloc PE / Size       119184 / 465.56 GiB
   Free  PE / Size       0 / 0
   VG UUID               ArnNRu-PQ9J-Lb4L-V4b6-4uBh-qhOZ-1W3F3D

[root at myws ~]#


[root at myws ~]# lvdisplay
   --- Logical volume ---
   LV Name                /dev/vg_myws1/lv_data
   VG Name                vg_myws1
   LV UUID                Ogx40d-zQkZ-PFfQ-hIdD-70Ob-7gba-CRcifJ
   LV Write Access        read/write
   LV Status              available
   # open                 1
   LV Size                448.56 GiB
   Current LE             114832
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           253:5

   --- Logical volume ---
   LV Name                /dev/vg_myws1/lv_root
   VG Name                vg_myws1
   LV UUID                VPRf8n-AjVk-Pk5g-9oGx-ia6H-KE1D-u8fve2
   LV Write Access        read/write
   LV Status              available
   # open                 1
   LV Size                11.72 GiB
   Current LE             3000
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           253:0

   --- Logical volume ---
   LV Name                /dev/vg_myws1/lv_swap
   VG Name                vg_myws1
   LV UUID                bvdAEw-7Afa-oYak-PYpQ-cTpL-BBhq-RUqFHj
   LV Write Access        read/write
   LV Status              available
   # open                 1
   LV Size                5.28 GiB
   Current LE             1352
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           253:1

[root at myws ~]#


As you can see from the boot-log, the system has 4 CPUs, which made me 
think that this is a "write barriers" issue, but from kernel 2.6.31 on, 
write barriers in multi processor systems should pose no problems any more.


questions:
1. is this a heavy issue, i.e. does this "error" corrupt my system with 
time?

2. what can i do to avoid this ext4 error, it it were an error? going 
back to ext3 is considered no solution.

thanks for any hints.


suomi





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