Difference between ext2 ext3 and ext4 File System | How To Convert ext2 to ext3 | Journaling File System

Ext2 is Best one compare to Ext3 File system

It will give the special Features in Availability, Data Integrity,Speed, Easy Transition

Advantages of Ext3 File system Over ext2 File system.
Availability If the system shutdown like unexpected power failure, System Crash, before it is mounted it will check the e2fsck program. It will check the inode..,For today’s files temGiga Bytes, it will take long time to check the whole files.

But in the ext3 it does not require the file system check even in the unclean system shutdown; It will provide Better consistent (steady, Reliable) compare to the ext2 file system. The time to recover does not depend on size and no o file it is depends on the Journal size.(Journaling process file system log convert file system during disk, if any problem arise it will be reconstructed it will be done by tune2fs tune to ext3 file system,While the power failure occur, Journalism File system restore pre-crash data store on the disk. It will also restore unsaved data.)

Integrity  It will provide the Guarantee Data Integrity file system in the Ext3.Even though after the system unclean shutdown data will not move the garbage .

Speed & Fast Ext3 file system it is provide higher Faster throughput- (time form input to output) compare to ext2.
Because it provides ex3 journaling optimize.

Easy Transition
It is easy to convert from ext2 to ext3 file system.
For this conversion it will not act as long tedious issue.
We can convert using tune2fs Linux command

ext2 To start the booting process is very slow compare to ext3 file system
For booting and retrieving the data while crashing disk speed is very slow compare to ext3 file system.

How To convert Ext2 Ext3 File system
Using tune2fs command we can convert ext2 to ext3 and ext3 to ext2 file system.
Ext3 to ext2 Journaling file system.
#tune2fs -O ^has_journal /dev/hda10
-O ^has_journal >> it will remove the journling option from the pariticular prition
^has_journal maintain the journal file system even across the unclean shutdown.
Ext2 to Ext3 File systems
#tune2fs -j /dev/hda2
While convert ext2 to ext3 it will add the journaling file system to the ext3.
-j it will add the Jornline option to the partition

How to Remove the File system Features like has_journal ext_attr resize_inode filetype needs_recovery
11.2)#tune2fs -l /dev/hdc1
Filesystem features: has_journal ext_attr resize_inode filetype needs_recovery sparse_super large_file
If you want to remove any of feature you can try with following command
# tune2fs -O ^dir_index /dev/hdc1 

Advantage of Ext4 file system
1) support huge individual  file and file system size.
Individual file size 16GB to 16 TB
ext4 file system size is 1EB (exabyte)=1024(PB)
2)Directory can contain maximum of 64,000 sub directories(as opposed to 32,000) in ext3
Note : if we create more than specified directory will get following error message "mkdir: cannot create directory `redhat-folder': Too many links"
3)New Features are introduced in ext4 file system
1)mulitblock allocation, 2)delayed allocation,3)journal checksum, 4)fask fsck.
these ext4 file system new features,performance,reliability, we know
when we compare to ext3 file system.
4)have the option to turn off journalism features "off"
5)to use ext4 file system there is no need to upgrade.
#mkfs.ext3 /dev/sda1
Converting ext3 to ext4.
#tune2fs -O extents,uninit_bg,dir_index Device_path
-O Add the new features
-O ^ Remote the Features.

 About e2fsck  

1)e2fsck is used to check & Repair second exteded file system(ext2fs).
2)it is used to check inodes, block and sizes.
-n option just for check But it won't fix the block. No changes will happend in that device.
#e2fsck -f /device_path
it will check
PASS 1)inode, blocks,sizes,
PASS 2)directory structure
PASS 3)directory connectivity
PASS 4)Reference Counts
PASS 5)Group summary information.
-f Forcefully check
-C 0  Display the progress what is Happening Background
-p without Confirmation to check the file system (-n no -y yes)
-v Verbose Mode (Print the details )

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