Xubuntu liveCD 11.04 running on "bad machine" with mdadm RAID1 array with an unrecognizable ext4 filesystem:
To rescue some files, I installed a new hard drive and formatted it to ext4. I copied 300GB worth of files retrieved from bad machine data scraping onto the newly formatted ext4 drive. I powered down the machine and removed the HDD, connected HDD to an ubuntu "good machine".
Good machine doesn't recognize the ext4 filesystem. Trying to mount, dmesg reports:
EXT3-fs (sdd1): error: can't find ext3 filesystem on dev sdd1.
EXT4-fs (sdd1): VFS: Can't find ext4 filesystem
EXT4-fs (sdd1): VFS: Can't find ext4 filesystem
So I put the drive back in the bad machine, and the filesystem is recognized and mountable.
Experimenting, I formatted another new drive to ext4 on good machine, then installed the drive on bad machine. Bad machine doesn't recognize new drive formatted by good machine.
What could cause bad machine to speak it's own ext4 language? Can the ext4 filesystem that bad machine is creating be corrected on good machine so the data can be copied onto good machine?
Edit 0
As requested by @bersh, command output on "bad machine":
# cat /proc/filesystems
nodev sysfs
nodev rootfs
nodev bdev
nodev proc
nodev cgroup
nodev cpuset
nodev tmpfs
nodev devtmpfs
nodev debugfs
nodev securityfs
nodev sockfs
nodev pipefs
nodev anon_inodefs
nodev devpts
ext3
ext2
ext4
nodev ramfs
nodev hugetlbfs
nodev ecryptfs
nodev fuse
fuseblk
nodev fusectl
nodev pstore
nodev mqueue
btrfs
iso9660
nodev overlayfs
squashfs
and the next one:
# lsmod|grep ext
#
(no output)
UPDATE 1
I realized I have been doing something wrong... The raid array is partitioned, I've been assembling the entire /dev/sda disk with mdadm when I should be assembling individual partitions: mdadm -A /dev/sda1 /dev/md5 and mdadm -A /dev/sda2... That doesn't answer the question though. because the non-raid ext4 partition was unrecognized on the good machine, and even if I correctly assemble the raid array, I might not be able to transfer it to a different machine and the different machine be able to recognize the ext4.
cat /proc/filesystems
andlsmod|grep ext
?mke2fs
)?