#include <stddisclaimer.h>
WARNING!! Before trying this tip on a production partition without a backup you might want to read this thread.
Goal #1: Add free space from end of drive to "/" file system which is
part of a logical volume. Part of this is done from the rescue CD
but you could do all of it from the rescue CD if you wanted. Commands
in red are in rescue mode.
Goal #2: Reverse the above process and shrink the logical volume and root file system to create free space at the end of a drive.
Prerequisites: Understand partition and file system basics.
Pros: Increase size of your root file system without backing up and deleting your partitions.
Cons: You should probably back up your system before doing this just in case. ;)
Let us begin:
Disk Before:
/dev/sda - 4GB Disk
/dev/sda1 - /boot 75MB
/dev/sda2 - LVM - VolGroup00
* /dev/VolGroup00/LogVol00 256MB SWAP
* /dev/VolGroup00/LogVol01 1.6GB /
Free Space - 2.0GB
Disk After:
/dev/sda - 4GB Disk
/dev/sda1 - /boot 75MB
/dev/sda2 - LVM - VolGroup00
/dev/sda3 - LVM - VolGroup00
* /dev/VolGroup00/LogVol00 256MB SWAP
* /dev/VolGroup00/LogVol01 3.6GB /
Free Space - 0GB
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Before:
Take note of partition info with fdisk:
[root@fc3 ~]# fdisk -l
Disk /dev/sda: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 230 1743052+ 8e Linux LVM
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Take note of file system info with df:
[root@fc3 ~]# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol01
1419128 575544 771496 43% /
/dev/sda1 101086 9045 86822 10% /boot
none 128056 0 128056 0% /dev/shm
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Take note of volume group info with vgdisplay:
[root@fc3 ~]# vgdisplay
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 1.66 GB
PE Size 32.00 MB
Total PE 53
Alloc PE / Size 52 / 1.62 GB
Free PE / Size 1 / 32.00 MB
VG UUID XQ5u33-HIGu-rRv0-Bwbk-vqGl-wc8Z-SCTJQg
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Take note of logical volume info info with lvdisplay:
[root@fc3 ~]# lvdisplay
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID HD1Sv3-kMLd-6VzL-Gh9s-poNm-A3hv-wgGS7I
LV Write Access read/write
LV Status available
# open 1
LV Size 1.38 GB
Current LE 44
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID FiV0q0-EFIF-jq9b-W2WE-Jd5r-m1AE-ILi1ZL
LV Write Access read/write
LV Status available
# open 1
LV Size 256.00 MB
Current LE 8
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:1
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Take note of physical volume info info with pvdisplay:
[root@fc3 ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name VolGroup00
PV Size 1.66 GB / not usable 0
Allocatable yes
PE Size (KByte) 32768
Total PE 53
Free PE 1
Allocated PE 52
PV UUID JzVt2G-IHhe-33EN-xOCu-1nay-pIhs-3jb55M
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The *scan utils also display useful information:
[root@fc3 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [1.66 GB / 32.00 MB free]
Total: 1 [1.66 GB] / in use: 1 [1.66 GB] / in no VG: 0 [0 ]
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[root@fc3 ~]# lvscan
ACTIVE '/dev/VolGroup00/LogVol01' [1.38 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol00' [256.00 MB] inherit
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[root@fc3 ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup00" using metadata type lvm2
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Delete partition and create new larger partition with fdisk (be careful to use the same "first cylinder" in both old and new):
[root@fc3 ~]# fdisk /dev/sda
Command (m for help): p (list partitions)
Disk /dev/sda: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 230 1743052+ 8e Linux LVM
Command (m for help): n (new partition)
Command action
e extended
p primary partition (1-4)
p (primary partition)
Partition number (1-4): 3 (partition #3)
First cylinder (231-522, default 231): <ENTER> (start cyl = 231)
Using default value 231
Last cylinder or +size or +sizeM or +sizeK (231-522, default 522): <ENTER> (last cyl = 522)
Using default value 522
Command (m for help): t (change partition type)
Partition number (1-4): 3 (on partition #3)
Hex code (type L to list codes): 8e (to Linux LVM)
Changed system type of partition 3 to 8e (Linux LVM)
Command (m for help): p (list partitions)
Disk /dev/sda: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 230 1743052+ 8e Linux LVM
/dev/sda3 231 522 2345490 8e Linux LVM
Command (m for help): w (write our changes to disk)
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
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Reboot:
Create the new physical volume on the new partition:
[root@fc3 ~]# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created
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Add the new physical volume to the volume group:
[root@fc3 ~]# vgextend VolGroup00 /dev/sda3
Volume group "VolGroup00" successfully extended
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Check our work so far with pvscan:
[root@fc3 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [1.66 GB / 32.00 MB free]
PV /dev/sda3 VG VolGroup00 lvm2 [2.22 GB / 2.22 GB free]
Total: 2 [3.88 GB] / in use: 2 [3.88 GB] / in no VG: 0 [0 ]
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Increase the size of the logical volume:
[root@fc3 ~]# lvextend -L+2.22G /dev/VolGroup00/LogVol01
Rounding up size to full physical extent 2.25 GB
Extending logical volume LogVol01 to 3.62 GB
Logical volume LogVol01 successfully resized
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Activate the changes to the volume group:
[root@fc3 ~]# lvm vgchange -a y VolGroup00
2 logical volume(s) in volume group "VolGroup00" now active
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Activate the changes to the logical volume:
[root@fc3 ~]# lvm lvchange -a y /dev/VolGroup00/LogVol01
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Reboot with Rescue CD (Find Installation):
rescue screenshot
Unmount sysimage (our root file system):
sh-3.00# umount /mnt/sysimage/sys
sh-3.00# umount /mnt/sysimage/dev
sh-3.00# umount /mnt/sysimage/proc
sh-3.00# umount /mnt/sysimage/boot
sh-3.00# umount /mnt/sysimage
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Check the existing file system for errors:
e2fsck screenshot
sh-3.00# e2fsck -f /dev/VolGroup00/LogVol01
e2fsck 1.35 (28-Feb-2004)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/VolGroup00/LogVol01: 32235/180224 files (1.5% non-contiguous), 148616/360448 blocks
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Resize the root (/) file system:
sh-3.00# resize2fs /dev/VolGroup00/LogVol01
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And there was light!
Reboot:
After:
Check our work with the various commands we used before:
[root@fc3 ~]# vgdisplay
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 3.88 GB
PE Size 32.00 MB
Total PE 124
Alloc PE / Size 124 / 3.88 GB
Free PE / Size 0 / 0
VG UUID XQ5u33-HIGu-rRv0-Bwbk-vqGl-wc8Z-SCTJQg
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Bigger numbers, that's gotta be a good sign:
[root@fc3 ~]# lvdisplay
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID HD1Sv3-kMLd-6VzL-Gh9s-poNm-A3hv-wgGS7I
LV Write Access read/write
LV Status available
# open 1
LV Size 3.62 GB
Current LE 116
Segments 3
Allocation inherit
Read ahead sectors 0
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID FiV0q0-EFIF-jq9b-W2WE-Jd5r-m1AE-ILi1ZL
LV Write Access read/write
LV Status available
# open 1
LV Size 256.00 MB
Current LE 8
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:1
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Bigger numbers here too:
[root@fc3 ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name VolGroup00
PV Size 1.66 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 53
Free PE 0
Allocated PE 53
PV UUID JzVt2G-IHhe-33EN-xOCu-1nay-pIhs-3jb55M
--- Physical volume ---
PV Name /dev/sda3
VG Name VolGroup00
PV Size 2.22 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 71
Free PE 0
Allocated PE 71
PV UUID njSXJM-7xDm-V72u-xn6M-Ruyg-jVL3-LY9RkA
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Not very interesting:
[root@fc3 ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup00" using metadata type lvm2
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Look mom, bigger numers:
[root@fc3 ~]# lvscan
ACTIVE '/dev/VolGroup00/LogVol01' [3.62 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol00' [256.00 MB] inherit
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An extra PV shows up here:
[root@fc3 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [1.66 GB / 0 free]
PV /dev/sda3 VG VolGroup00 lvm2 [2.22 GB / 0 free]
Total: 2 [3.88 GB] / in use: 2 [3.88 GB] / in no VG: 0 [0 ]
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Our ultimate goal has been achieved, more free space in "/":
[root@fc3 ~]# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol01
3741400 570228 3019132 16% /
/dev/sda1 101086 9045 86822 10% /boot
none 128056 0 128056 0% /dev/shm
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And it was good...
I also reversed the above process and shrunk things down to original sizes with free space at the end of the drive (all from the rescue CD):
Boot Rescue CD:
Unmount sysimage:
# umount /mnt/sysimage/sys
# umount /mnt/sysimage/dev
# umount /mnt/sysimage/proc
# umount /mnt/sysimage/boot
# umount /mnt/sysimage
Reduce the file system (smaller than needed for safety):
1) # e2fsck -f /dev/VolGroup00/LogVol01
2) # resize2fs /dev/VolGroup00/LogVol01 1400000K
3) # e2fsck -f /dev/VolGroup00/LogVol01
Reduce the logical volume to 44 extents:
4) # lvm lvdisplay
5) # lvm lvreduce -l44 /dev/VolGroup00/LogVol01
Activate changes:
6) # lvm lvchange -a y /dev/VolGroup00/LogVol01
Reduce the volume group:
7) # lvm vgreduce VolGroup00 /dev/sda3
8) # lvm vgchange -a y VolGroup00
Remove the /dev/sda3 PV:
9) # lvm pvremove /dev/sda3
Delete the /dev/sda3 partition:
10) # fdisk /dev/hda
d
3
w
Reboot back into rescue CD:
11) # exit
Unmount sysimage:
# umount /mnt/sysimage/sys
# umount /mnt/sysimage/dev
# umount /mnt/sysimage/proc
# umount /mnt/sysimage/boot
# umount /mnt/sysimage
Enlarge file system to full capacity of logical volume:
12) # e2fsck -f /dev/VolGroup00/LogVol01
13) # resize2fs /dev/VolGroup00/LogVol01
14) # e2fsck -f /dev/VolGroup00/LogVol01
Reboot without rescue CD
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Notice when booted from the rescue CD I prefaced the lv*/pv*/vg* commands with "lvm". On a fully installed system all of these commands are really just symbolic links to the "lvm" command and when called via the other names lvm knows to act accordingly. On the rescue CD these symbolic links do not exist but you can just pass the command you want to run as the first parameter to the lvm command to get the same result. Sorry I didn't break the shrink process down into more detail like I did with the enlarging process but since I was booted from the rescue CD I didn't have the copy/paste capabilities, and I'm lazy. I might clean it up later. I highly recommend that you look at the section in the LVM HOWTO for each task that we have performed. It's a very good document.
Further Reading:
fdisk/partition HOWTO(Excellent Resource)
LVM HOWTO (Excellent Resource)
FedoraForum Thread #1
FedoraForum Thread #2
$ man lvm
Have fun!
Forums
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