Sadly Ubuntu does not have LVM enabled in the default install, as this whole issue would be solved with a simple pvmigrate and lvresize...
My /home (which is on a separate /dev/sda5 partition) is filling up.
The availability of Steam on Linux gave it the final blow: it's time to bring in another partition.
As I don't want to commit a whole partition to /home, I've mounted /dev/sdc2 as /space and I'm going to create a symlink to an home subdirectory.
First, boot Ubuntu in rescue mode and select root shell.
Mount all filesystems
#mount -a
note that mounted filesystem won't be visible with a df, but you should cat /proc/mounts to see them
Set proper permission to the new partition
#chown root:root /space
#chmod 755 /space
Then create the new home and copy the old one
#mkdir /space/home
#cp -a /home/* /space/home/
Mount / read/write as we'll need to modify the fstab
#mount / -o rw,remount
#vi /etc/fstab
Comment the old /home
Remove the old home mount point and create the new symlink
#umount /home
#rmdir /home
#ls -s /space/home /home
Reboot
Showing posts with label lvm. Show all posts
Showing posts with label lvm. Show all posts
2012-12-30
2011-12-04
Shrinking the root filesystem
The default install of RedHat 5 fills the entire disk with the root filesystem: this may backfire later during machine lifetime.
Here's a way to resize the root filesystem.
Note that while the size increase can be done online, as of RedHat 5, size reduction must be performed in rescue mode.
Here's a tipical installation:
# df -h
The physical volume is full, with 0 free extents.
We are going to reduce / size to 6GB.
Boot in rescue mode
Skip existing installation detection.
Activate existing volume groups:
Run a filesystem check before resizing:
Set the filesystem size a litte less than required, so the resizing of the underlying logical volume won't cut short the filesystem itself.
Resize the logical volume to the target size.
Now resize again the filesystem without giving any size, so it will fill up the logical volume.
Reboot back into the system.
You can see the new / size:
And the physical volume now has some spare space left.
Here's a way to resize the root filesystem.
Note that while the size increase can be done online, as of RedHat 5, size reduction must be performed in rescue mode.
Here's a tipical installation:
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
7.7G 3.1G 4.3G 42% /
/dev/sda1 99M 19M 75M 21% /boot
tmpfs 502M 0 502M 0% /dev/shm
# vgdisplay -v
Finding all volume groups
Finding volume group "VolGroup00"
--- 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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 316 / 9.88 GB
Free PE / Size 0 / 0
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 7.91 GB
Current LE 253
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 0
The physical volume is full, with 0 free extents.
We are going to reduce / size to 6GB.
Boot in rescue mode
boot: linux rescue
Skip existing installation detection.
Activate existing volume groups:
# lvm vgscan
# lvm vgchange -ay /dev/VolGroup00
Run a filesystem check before resizing:
# e2fsck -f /dev/VolGroup00/LogVol00
Set the filesystem size a litte less than required, so the resizing of the underlying logical volume won't cut short the filesystem itself.
# resize2fs /dev/VolGroup00/LogVol00 5G
Resize the logical volume to the target size.
# lvm lvresize -L 6G /dev/VolGroup00/LogVol00
Now resize again the filesystem without giving any size, so it will fill up the logical volume.
# resize2fs /dev/VolGroup00/LogVol00
Reboot back into the system.
You can see the new / size:
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
5.9G 3.1G 2.7G 54% /
/dev/sda1 99M 19M 75M 21% /boot
tmpfs 502M 0 502M 0% /dev/shm
# vgdisplay -v
Finding all volume groups
Finding volume group "VolGroup00"
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 255 / 7.97 GB
Free PE / Size 61 / 1.91 GB
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 6.00 GB
Current LE 192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 61
And the physical volume now has some spare space left.
2011-11-27
Boot disk transplant
Bare hands, MacGyver-style, boot disk transplant.
I've used a network attached linux machine as a temporary storage, but a local USB disk will do as fine.
The new disk should be as least as big as the old one.
First take note of the original disk configuration.
You will need the partition table:
The volume group configuration (note the PE and the LE sizes)
# vgdisplay -v
Finding all volume groups
/dev/hda: open failed: No medium found
Finding volume group "VolGroup00"
--- 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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 316 / 9.88 GB
Free PE / Size 0 / 0
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 7.91 GB
Current LE 253
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 0
And the fstab:
you will have to rebuild the logical volumes that belong to the transplanting disk
Boot the machine in rescue mode to do a full backup
Start the network interface and do not mount any filesystem.
Backup the filesystems on /dev/sda and send them to the second machine via network.
#gzip -1 </dev/VolGroup00/LogVol00 | ssh user@secondmachine "cat >root.gz"
Turn off the first machine, remove the old hd and put the new one.
Reboot again into linux rescue, with networking and without searching for existing installations.
Use fdisk to rebuild the same layout, with identical partitions, cylinder boundaries and partition Id (8e for LVM)
Now rebuild the LVM
Note the PE size:
and the LV size
Rebuild the swap partition
and write back the previous backups:
Reboot once again in rescue mode
#chroot /mnt/sysimage
#grub-install /dev/sda
And finally reboot with your new disk.
Note that if the new disk is bigger than the old one, you will have some unpartitioned space left.
You can partition it with fdisk, pvcreate, and add it to LVM.
I've used a network attached linux machine as a temporary storage, but a local USB disk will do as fine.
The new disk should be as least as big as the old one.
First take note of the original disk configuration.
You will need the partition table:
# fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 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 1305 10377990 8e Linux LVM
The volume group configuration (note the PE and the LE sizes)
# vgdisplay -v
Finding all volume groups
/dev/hda: open failed: No medium found
Finding volume group "VolGroup00"
--- 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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 316 / 9.88 GB
Free PE / Size 0 / 0
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 7.91 GB
Current LE 253
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 0
And the fstab:
# cat /mnt/sysimage/etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
you will have to rebuild the logical volumes that belong to the transplanting disk
Boot the machine in rescue mode to do a full backup
boot: linux rescue
Start the network interface and do not mount any filesystem.
Backup the filesystems on /dev/sda and send them to the second machine via network.
#gzip -1 </dev/VolGroup00/LogVol00 | ssh user@secondmachine "cat >root.gz"
#gzip -1 </dev/sda1 | ssh user@secondmachine "cat >boot.gz"
Turn off the first machine, remove the old hd and put the new one.
Reboot again into linux rescue, with networking and without searching for existing installations.
Use fdisk to rebuild the same layout, with identical partitions, cylinder boundaries and partition Id (8e for LVM)
Now rebuild the LVM
#lvm pvcreate /dev/sda2
Note the PE size:
#lvm vgcreate -s 32M VolGroup00 /dev/sda2
and the LV size
#lvm lvcreate -l 253 -n LogVol00 VolGroup00
#lvm lvcreate -l 63 -n LogVol01 VolGroup00
Rebuild the swap partition
#mkswap /dev/VolGroup00/LogVol01
and write back the previous backups:
#ssh user@secondmachine "cat boot.gz" | gzip -d > /dev/sda1
#ssh user@secondmachine "cat root.gz" | gzip -d > /dev/VolGroup00/LogVol00Reboot once again in rescue mode
#chroot /mnt/sysimage
#grub-install /dev/sda
And finally reboot with your new disk.
Note that if the new disk is bigger than the old one, you will have some unpartitioned space left.
You can partition it with fdisk, pvcreate, and add it to LVM.
The broken LVM boot mirror
I was experimenting with LVM mirroring of the root partition and I've discovered that it won't fail gracefully.
After successfully setting up a mirror of LogVol00 to a second hd, I've rebooted the machine without the second hard disk.
I was expecting a normal boot from the first hd, which was the one with the grub and the boot partition.
I've got a kernel panic instead.
To recover the system I had to boot in rescue mode
boot: linux rescue
The rescue mode won't find any linux partition even if asked to search for them.
So back to the shell:
lvm pvscan
The system complained about an unknown device within VolGroup00
All logical volumes were marked as inactive
So, force the volume group activation
lvm vgchange -ay --partial VolGroup00
Now we can remove the missing mirror copy from the volume group
lvm vgreduce --removemissing --force VolGroup00
and the mirror logical volume will be converted back to linear.
Reboot.
After successfully setting up a mirror of LogVol00 to a second hd, I've rebooted the machine without the second hard disk.
I was expecting a normal boot from the first hd, which was the one with the grub and the boot partition.
I've got a kernel panic instead.
To recover the system I had to boot in rescue mode
boot: linux rescue
The rescue mode won't find any linux partition even if asked to search for them.
So back to the shell:
lvm pvscan
The system complained about an unknown device within VolGroup00
lvm vgscan
lvm lvscanAll logical volumes were marked as inactive
So, force the volume group activation
lvm vgchange -ay --partial VolGroup00
Now we can remove the missing mirror copy from the volume group
lvm vgreduce --removemissing --force VolGroup00
and the mirror logical volume will be converted back to linear.
Reboot.
2011-11-26
2011-11-25
How to rename the root volume group
This was tested on a RedHat 5.4
Boot the machine with installation CD into rescue mode
boot: linux rescue
at the request of mounting the existing installation, choose skip
Activate the volume group with
#lvm pvscan
#lvm vgscan
Now you can rename the volume group
#lvm vgrename VolGroup00 VolGroup99
Now you must change all the references to VolGroup00 on the filesytem to the new volume group name.
Activate the new volume group
#lvm vgchange -ay VolGroup99
Mount the root and the boot filesystems
#mkdir -p /mnt/sysimage
#mount /dev/VolGroup99/LogVol00 /mnt/sysimage
Mount the boot filesystems (note that the device name may vary according to your actual boot device)
#mount /dev/sda1 /mnt/sysimage/boot
Edit the fstab to look like this
#vi /mnt/sysimage/etc/fstab
/dev/VolGroup99/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup99/LogVol01 swap swap defaults 0 0
and the grub configuration
#vi /mnt/sysimage/boot/grub/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup99/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-164.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-164.el5 ro root=/dev/VolGroup99/LogVol00 rhgb quiet
initrd /initrd-2.6.18-164.el5.img
Now reboot once again in rescue mode.
This time choose to mount the filesystem onto /mnt/sysimage (not in read only)
Finally, rebuild the initrd image, as it yet contains the old fstab, matching your kernel version
#chroot /mnt/sysimage
#mkinitrd -v -f /boot/initrd-2.6.18-164.el5.img 2.6.18-164.el5
Reboot into your newly renamed system.
Note: if you don't reboot into rescue mode before rebuilding the initial ram disk, the mkinitrd will fail as it won't find the new /dev/VolGroup99 pseudo files
Boot the machine with installation CD into rescue mode
boot: linux rescue
at the request of mounting the existing installation, choose skip
Activate the volume group with
#lvm pvscan
#lvm vgscan
Now you can rename the volume group
#lvm vgrename VolGroup00 VolGroup99
Now you must change all the references to VolGroup00 on the filesytem to the new volume group name.
Activate the new volume group
#lvm vgchange -ay VolGroup99
Mount the root and the boot filesystems
#mkdir -p /mnt/sysimage
#mount /dev/VolGroup99/LogVol00 /mnt/sysimage
Mount the boot filesystems (note that the device name may vary according to your actual boot device)
#mount /dev/sda1 /mnt/sysimage/boot
Edit the fstab to look like this
#vi /mnt/sysimage/etc/fstab
/dev/VolGroup99/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup99/LogVol01 swap swap defaults 0 0
and the grub configuration
#vi /mnt/sysimage/boot/grub/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup99/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-164.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-164.el5 ro root=/dev/VolGroup99/LogVol00 rhgb quiet
initrd /initrd-2.6.18-164.el5.img
Now reboot once again in rescue mode.
This time choose to mount the filesystem onto /mnt/sysimage (not in read only)
Finally, rebuild the initrd image, as it yet contains the old fstab, matching your kernel version
#chroot /mnt/sysimage
#mkinitrd -v -f /boot/initrd-2.6.18-164.el5.img 2.6.18-164.el5
Reboot into your newly renamed system.
Note: if you don't reboot into rescue mode before rebuilding the initial ram disk, the mkinitrd will fail as it won't find the new /dev/VolGroup99 pseudo files
2011-10-08
Migrating logical volumes between volume groups
Some time ago I added a second hard disk to my machine and I joined it to the root volume group. I've also created a logical volume with a /data filesystem on it.
Now I need to move that data disk to a new machine, but as long as it's part of the root volume group I can't easily move it without making the whole machine unbootable.
These are the steps on a Red Hat 5.4 machine:
First, make sure that the disk you want to migrate does not contains logical volumes that are spanned on other disks also: I checked it with the system-config-lvm GUI, that shows how logical volumes are mapped to physical volumes, and I saw that my logical volume lv_data was entirely on /dev/sdb.
This is the initial fstab with the /data mounted from VolGroup00
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/dev/VolGroup00/lv_data /data ext3 defaults 1 2
first, unmount the /data filesystem as this whole operation can't be done online.
[root@testlvm /]#umount /data
deactivate the logical volume
[root@testlvm /]#lvchange -an /dev/VolGroup00/lv_data
now split the root volume group creating a new VG_data
[root@testlvm /]# vgsplit VolGroup00 VG_data /dev/sdb
New volume group "VG_data" successfully split from "VolGroup00"
you can see that the logical volume lv_data now belongs to the newly created volume group.
if you get an error, read at the bottom of this post.
[root@testlvm /]# vgdisplay -v
Finding all volume groups
Finding volume group "VG_data"
--- Volume group ---
VG Name VG_data
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1.97 GB
PE Size 32.00 MB
Total PE 63
Alloc PE / Size 63 / 1.97 GB
Free PE / Size 0 / 0
VG UUID 67mnJx-WyyP-7XQz-D1na-CNhr-rjUJ-79V8Fu
--- Logical volume ---
LV Name /dev/VG_data/lv_data
VG Name VG_data
LV UUID lcwb7r-n0YZ-lslK-HoqE-VL6V-IMNl-rIY6N0
LV Write Access read/write
LV Status NOT available
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
--- Physical volumes ---
PV Name /dev/sdb
PV UUID uwiyVE-Hkvt-dG3c-x1Ak-KBng-T91O-5Xuz2l
PV Status allocatable
Total PE / Free PE 63 / 0
Finding volume group "VolGroup00"
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 6
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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 316 / 9.88 GB
Free PE / Size 0 / 0
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 7.91 GB
Current LE 253
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 0
bring back online the logical volume
[root@testlvm /]#lvchange -ay /dev/VG_data/lv_data
note that you can't use TAB to complete the path of the logical volume, because the dev node won't be created until you activate it, so just type it as it is.
edit /etc/fstab with new new mount point
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/dev/VG_data/lv_data /data ext3 defaults 1 2
and finally mount the /data filesystem from his new home
[root@testlvm /]#mount /data
now you can safely umount it, export the volume group and reimport it on another machine.
Note that as of Red Hat 5.4 you may get a an error on the vgsplit command if the target volume group already exists and has active logical volumes.
Logical volumes in "VolGroup00" must be inactive
The error message is somewhat misleading: you'll get it even if the logical volumes you are migrating are already inactive.
Workaround: just make it in 2 steps: first split into a new "temp" volume group, then vgmerge the "temp" volume group into the target volume group.
Now I need to move that data disk to a new machine, but as long as it's part of the root volume group I can't easily move it without making the whole machine unbootable.
These are the steps on a Red Hat 5.4 machine:
First, make sure that the disk you want to migrate does not contains logical volumes that are spanned on other disks also: I checked it with the system-config-lvm GUI, that shows how logical volumes are mapped to physical volumes, and I saw that my logical volume lv_data was entirely on /dev/sdb.
This is the initial fstab with the /data mounted from VolGroup00
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/dev/VolGroup00/lv_data /data ext3 defaults 1 2
first, unmount the /data filesystem as this whole operation can't be done online.
[root@testlvm /]#umount /data
deactivate the logical volume
[root@testlvm /]#lvchange -an /dev/VolGroup00/lv_data
now split the root volume group creating a new VG_data
[root@testlvm /]# vgsplit VolGroup00 VG_data /dev/sdb
New volume group "VG_data" successfully split from "VolGroup00"
you can see that the logical volume lv_data now belongs to the newly created volume group.
if you get an error, read at the bottom of this post.
[root@testlvm /]# vgdisplay -v
Finding all volume groups
Finding volume group "VG_data"
--- Volume group ---
VG Name VG_data
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1.97 GB
PE Size 32.00 MB
Total PE 63
Alloc PE / Size 63 / 1.97 GB
Free PE / Size 0 / 0
VG UUID 67mnJx-WyyP-7XQz-D1na-CNhr-rjUJ-79V8Fu
--- Logical volume ---
LV Name /dev/VG_data/lv_data
VG Name VG_data
LV UUID lcwb7r-n0YZ-lslK-HoqE-VL6V-IMNl-rIY6N0
LV Write Access read/write
LV Status NOT available
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
--- Physical volumes ---
PV Name /dev/sdb
PV UUID uwiyVE-Hkvt-dG3c-x1Ak-KBng-T91O-5Xuz2l
PV Status allocatable
Total PE / Free PE 63 / 0
Finding volume group "VolGroup00"
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 6
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 9.88 GB
PE Size 32.00 MB
Total PE 316
Alloc PE / Size 316 / 9.88 GB
Free PE / Size 0 / 0
VG UUID CJqD4r-kRQM-Cj9e-XwOr-6dn8-TkPH-MfTTyZ
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID d4iToX-8m0c-jf9s-sMMN-VDpO-brE8-4kWhf2
LV Write Access read/write
LV Status available
# open 1
LV Size 7.91 GB
Current LE 253
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID kEzo7d-AHuv-xiPD-3Qbo-v8yY-6w1D-DFMIwN
LV Write Access read/write
LV Status available
# open 1
LV Size 1.97 GB
Current LE 63
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Physical volumes ---
PV Name /dev/sda2
PV UUID 7bPvQd-H8yE-v00N-asPT-WQ92-6oCS-bBh6nj
PV Status allocatable
Total PE / Free PE 316 / 0
bring back online the logical volume
[root@testlvm /]#lvchange -ay /dev/VG_data/lv_data
note that you can't use TAB to complete the path of the logical volume, because the dev node won't be created until you activate it, so just type it as it is.
edit /etc/fstab with new new mount point
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/dev/VG_data/lv_data /data ext3 defaults 1 2
and finally mount the /data filesystem from his new home
[root@testlvm /]#mount /data
now you can safely umount it, export the volume group and reimport it on another machine.
Note that as of Red Hat 5.4 you may get a an error on the vgsplit command if the target volume group already exists and has active logical volumes.
Logical volumes in "VolGroup00" must be inactive
The error message is somewhat misleading: you'll get it even if the logical volumes you are migrating are already inactive.
Workaround: just make it in 2 steps: first split into a new "temp" volume group, then vgmerge the "temp" volume group into the target volume group.
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