View source for Resizing ext3/4 on LVM


=Check and prepare for resize=

First, check the size of the file system to see if it needs expanding

 [root@Linux01 ~]# pwd
 /TCPDumpLV
 [root@Linux01 TCPDumpLV]# df -kh .
 Filesystem
 	Size
 	Used 	Avail 	Use% 	Mounted on /dev/mapper/TCPDumpVolGRP-TCPDumpLV
 	3.1G
 	2.9G 	69M 	98% 	/TCPDumpLV

Note: The disk free command shows that we have 65MB available on our file system and that its 98% use.  If we don't take action soon, we risk filling the file system.

Let's find out which Volume Group contains the Logical Volume that holds /dev/mapper/TCPDumpVolGRP-TCPDumpLV

 [root@Linux01 ~]# lvdisplay /dev/TCPDumpVolGRP/TCPDumpLV
 --- Logical volume ---
 LV Name 	/dev/TCPDumpVolGRP/TCPDumpLV
 VG Name 	TCPDumpVolGRP
 LV UUID 	hYQs4t-YtY7-51hl-c4ps-4N6d-2W7h-IidcxF
 LV Write Access 	read/write
 LV Status 	available
 # open 	1
 LV Size 	3.12 GB
 Current LE 	100
 Segments 	1
 Allocation 	inherit
 Read ahead sectors 	auto
 - currently set to 	256
 Block device 	253:5

Note: You can see the volume group for this file system is TCPDumpVolGRP

Let's find out if the volume group TCPDumpVolGRP has available free space to allocate to the logical volume

 [root@Linux01 ~]# vgdisplay TCPDumpVolGRP
 --- Volume group ---
 VG Name 	TCPDumpVolGRP
 System ID 	
 Format 	lvm2
 Metadata Areas 	3
 Metadata Sequence No 	5
 VG Access 	read/write
 VG Status 	resizable
 MAX LV 	0
 Cur LV 	2
 Open LV 	2
 Max PV 	0
 Cur PV 	3
 Act PV 	3
 VG Size 	11.91 GB
 PE Size 	32.00 MB
 Total PE 	381
 Alloc PE / Size 	228 / 7.12 GB
 Free PE / Size 	153 / 4.78 GB
 VG UUID 	9fWFIS-vDlg-xOW6-Xmb8-Tkrg-GPZw-ZnUZwh

Note: This volume group has plenty of free space.  If we were out of physical extents, we would have to add additional physical volumes to this volume group before continuing on.

=Resize the logical volume=

We will now resize the logical volume TCPDumpLV by adding 3GB

 [root@Linux01 TCPDumpLV]# lvresize -L +3GB /dev/TCPDumpVolGRP/TCPDumpLV
 Extending logical volume TCPDumpLV to 6.12 GB
 Logical volume TCPDumpLV successfully resized
 [root@Linux01 TCPDumpLV]#

Inspect the new size of the logical volume

 [root@Linux01 ~]# lvdisplay /dev/TCPDumpVolGRP/TCPDumpLV
 --- Logical volume ---
 LV Name 	/dev/TCPDumpVolGRP/TCPDumpLV
 VG Name 	TCPDumpVolGRP
 LV UUID 	hYQs4t-YtY7-51hl-c4ps-4N6d-2W7h-IidcxF
 LV Write Access 	read/write
 LV Status 	available
 # open 	1
 LV Size 	6.12 GB
 Current LE 	196
 Segments 	2
 Allocation 	inherit
 Read ahead sectors 	auto
 - currently set to 	256
 Block device 	253:5 

 [root@Linux01 ~]# pwd
 /TCPDumpLV
 [root@Linux01 TCPDumpLV]# df -kh .
 Filesystem 
 	Size
 	Used 	Avail 	Use% 	Mounted on /dev/mapper/TCPDumpVolGRP-TCPDumpLV
 	3.1G
 	2.9G 	69M 	98% 	/TCPDumpLV

Note: You will notice that although we have increased the size of the logical volume, the size of the file system has been unaffected.
We now need to resize the ext3 file system to utilize the remaining available space within the logical volume

 [root@Linux01 TCPDumpLV]# resize2fs -p /dev/mapper/TCPDumpVolGRP-TCPDumpLV
 resize2fs 1.39 (29-May-2006)
 Filesystem at /dev/mapper/TCPDumpVolGRP-TCPDumpLV is mounted on /TCPDumpLV; on-line resizing required
 Performing an on-line resize of /dev/mapper/TCPDumpVolGRP-TCPDumpLV to 1605632 (4k) blocks.
 The filesystem on /dev/mapper/TCPDumpVolGRP-TCPDumpLV is now 1605632 blocks long.

 [root@Linux01 TCPDumpLV]# df -kh .
 Filesystem
 	Size
 	Used 	Avail 	Use% 	Mounted on /dev/mapper/TCPDumpVolGRP-TCPDumpLV
 	6.1G
 	2.9G 	2.9G 	50% 	/TCPDumpLV

=Resizing filesystems=

Resize ext3 filesystem
 resize2fs /dev/mapper/TCPDumpVolGRP-TCPDumpLV

Resize xfs filesystem

 mount /dev/mapper/TCPDumpVolGRP-TCPDumpLV /mnt/target
 xfs_growfs -d /mnt/target

[http://www.tcpdump.com/kb/os/linux/lvm-resizing-guide/all-pages.html]
[http://backdrift.org/online-ext3-grow-resize-with-lvm]
[http://tharindu.info/2011/05/22/grow-online-xfs-on-lvm]

=Shrinking ext2/3/4=

Shrinking[https://www.thegeekdiary.com/centos-rhel-how-to-shrink-lvm-root-file-system/] an ext3 volume is fairly straight forward, but it's important you don't mount your drive and start doing stuff, before you verify everything worked correctly.

resize the partition first

    1. e2fsck -f /dev/vg/lv1
    2. resize2fs -p /dev/vg/lv1 ###G
    3. e2fsck /dev/vg/lv1

use lvreduce to shrink the volume

    4. lvreduce -L ###G /dev/vg/lv1
    5. e2fsck /dev/vg/lv1

following extends to 100% of available space

    6. resize2fs -f /dev/vg/lv1 

Step #5 is the most important step; as steps 1-3 will not have any problems unless you have a system failure, a corrupted file system to start with, disk failure, or hardware failure.  Step 5 however, could be due to sys-admin error, from shrinking the LVM volume too much.  If you receive an error similar to the following, then you probably shrunk the volume too much, and your file system is not completely accessible.

    e2fsck 1.41.9 (22-Aug-2009)
    The filesystem size (according to the superblock) is 113634135 blocks
    The physical size of the device is 112197632 blocks
    Either the superblock or the partition table is likely to be corrupt!
    Abort<y>? cancelled!

If the error is due to shrinking too far, then this is easy to recover from; simply do another lvresize, with a large size specified, and do another e2fsck afterward.

Generally speaking, you should make the LVM maybe 2% or so larger than the file system was reduced to, so that there's room for file system overhead.

[http://blog.adamsbros.org/2010/01/11/safe-shrinking-of-lvm-volumes/]
[http://www.davidodwyer.com/content/howto-shrink-ext3-partition-lvm-free-available-extents]
[http://www.microhowto.info/howto/reduce_the_size_of_an_ext2_ext3_or_ext4_filesystem.html]