[CentOS] Ext3 filesystem access after downgrade from v4.2 to v3.6 [SOLVED]

Johnny Hughes mailing-lists at hughesjr.com
Thu Jan 26 11:25:02 UTC 2006


On Thu, 2006-01-26 at 11:18 +0000, Plant, Dean wrote:
> Peter Kjellström wrote:
> > On Monday 23 January 2006 16:46, Plant, Dean wrote:
> >> I need to downgrade a system from Centos x4.2 to v3.6 (x86) due to
> >> performance problems with Arkeia Network Backup and AIT-4 tape
> >> drives. The backup database is stored on a v4.2 created ext3
> >> partition. When accessing this partition after the downgrade, Centos
> >> complains on boot that 
> >> 
> >> fsck.ext3: Filesystem has unsupported feature(s) (/dev/sda5)
> >> *fsck: Get a newer version of e2fsck! [fail]
> > 
> > you can list the features with the command "tune2fs -l /dev/sda5" and
> > toggle features too (read the man page). It's most likely the
> > dir_index feature... 
> > 
> 
> Thanks Peter for the prod in the right direction.
> 
> A v4 filesystem shows these features
> 
> # tune2fs -l /dev/sda1 | grep features
> Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
> 
> A v3 filesystem has these features
> 
> # tune2fs -l /dev/sda5 | grep features
> Filesystem features:      has_journal filetype needs_recovery sparse_super
> 
> Tunes2fs from v4.2 can be used to remove "has_journal filetype dir_index sparse_super"
> 
> Booted into rescue mode with a v4.2 cd and removed dir_index but the v3.6 OS still complained.
> 
> After finding this link https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=145307 which references problems with ghost and v4 ext3 partitions I used debugfs to remove some of the other 4.2 specific features.
> 
> # debugfs -w /dev/sda5 -R "features ^resize_inode ^ext_attr"
> # fsck -y /dev/sda5
> 
> The v3.6 OS now boots correctly.
> 

Very good info :) ... 

It was probably the ext_attr that was causing you problems.  That is the
extra stuff required for SELinux/ACLs that we warn against for upgrading
a CentOS-3 box to CentOS-4.

> >> 
> >> If I comment the partition out of /etc/fstab the machine boots as
> >> normal and I can manually mount the filesystem.
> >> 
> >> My questions are:
> >> 
> >> If I use the v4.2 ext3 filesystem on v3.6 I am likely to corrupt the
> >> data?
> > 
> > I don't think you're running any risk of corrupting your data.
> > 
> > /Peter
> > 
> >> And what is the best way fix this problem? Do as it says and try
> >> and upgrade e2fsck or is there a better fix?
> >> 
> >> Thanks
> >> 
> >> Dean.

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