Reducing/Resizing LVM where "/" filesystem is included in the LVM

Hi,

I am a newbie to linux and I have XP and FC3 on my 30GB HD. I have searched through internet to find out how to reduce logical Volume based on LVM2, but as my situation is quite different hence could not find out any solution.
I have total 3 Primary partions and one extended partitions. first 3 primary paritions are NTFS(XP),FAT32(data) and NTFS(data) respectively.
Extended partition contains two partitions, linux boot and linux LVM. Linux LVM contains one Group Volume which contains two Logical Volumes. One Logical Volume has / root file System
and other Logical Volume has SWAP space.

Here is the ouput of fdisk -l and contents of /etc/fstab

fdisk -l
=======================================================================
Disk /dev/hda: 30.0 GB, 30005821440 bytes
255 heads, 63 sectors/track, 3648 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1         637     5116671    7  HPFS/NTFS
/dev/hda2             638        1274     5116702+   c  W95 FAT32 (LBA)
/dev/hda3            1275        2546    10217340    7  HPFS/NTFS
/dev/hda4            2547        3648     8851815    f  W95 Ext'd (LBA)
/dev/hda5            2547        2559      104391   83  Linux
/dev/hda6            2560        3648     8747361   8e  Linux LVM

=======================================================================

cat /etc/fstab
==========================================================================
# This file is edited by fstab-sync - see 'man fstab-sync' for details
/dev/VolGroup00/LogVol00 / ext3 defaults
1 1
LABEL=/boot /boot ext3 defaults
1 2
none /dev/pts devpts gid=5,mode=620
0 0
none /dev/shm tmpfs defaults
0 0
none /proc proc defaults
0 0
none /sys sysfs defaults
0 0
/dev/VolGroup00/LogVol01 swap swap defaults
0 0
/dev/hdb /media/cdrom auto
pamconsole,fscontext=system_u:object_r:removable_t,ro,exec,noauto,managed 0 0
/dev/fd0 /media/floppy auto
pamconsole,fscontext=system_u:object_r:removable_t,exec,noauto,managed 0 0

/dev/hda1   /mnt/win_ntfs_c     ntfs    ro,defaults,umask=0222 0 0
/dev/hda2   /mnt/win_fat32_d     auto    ro,defaults,umask=0222 0 0
/dev/hda3   /mnt/win_ntfs_e     ntfs    ro,defaults,umask=0222 0 0

================================================================================

Now I want to free some space from the linux LVM(hda6) and create a FAT32 partition as hda7.

So how to reduce that LVM?

one more questions my /boot parition is /dev/hda5 but in fstab it shows it as LABEL=/boot
so how is that?

Thanks.

-ajeet.

I suggest you use qtparted. Basically you need to:

1. Resize /
2. Move the swap volume back so it is adjacent to / (as it is swap, you could just run swapoff, delete the volume, and then recreate it.)
3. Reduce the physical volume size

I don't know if qtparted can do step 3 but it can do steps 1 and 2, I think.

/dev/hda5 contains a label called /boot. That means if you move /boot to a different partition, you don't have to change your fstab, which is useful, but rarely.

However, if you ever insert another Linux-formatted hard drive in your system, from a different computer, it can cause the OS to become very confused as it cannot determine which "/boot"-labelled partition to use! That is the disadvantage of partition labelling.

Robin

Oh and of course, to do this, you must be running a separate copy of Linux
- like a live CD. Knoppix, for example, boots with usually no user intervention required, and contains qtparted and everything it needs.

Robin

Thanks for the suggestions, but qtparted does not help.

I ran Knoppix Live CD 3.7 which has qtparted 0.4.4 and it does not recognizes the linux lvm partition and shows it as unknown type/filesystem in the list, and it does not give any other information or any other option(e.g resize) when i right click that partition.

so the question remains how to do it.

Thanks.

-ajeet.

[...]

The knoppix CD also has the commandline lvm utilities and ext2resize binaries. Have fun reading the manpages for vgscan, vgchange, ext2resize, lvreduce, pvmove, vgreduce, pvremove, fdisk, pvcreate, vgextend, and pvmove. Not necessarily in that order.

HTH.

Sam Vilain, sam /\T vilain |><>T net, PGP key ID: 0x05B52F13
(include my PGP key ID in personal replies to avoid spam filtering)

I am able to partialy solve my problem, so still needs help to complete it. This may be help full for newbie like me, so i am writing the steps here.

So first let me define again what i wanted to do.

So Robin Suggested:
======================

I suggest you use qtparted. Basically you need to:

1. Resize /
2. Move the swap volume back so it is adjacent to / (as it is swap, you could just run swapoff, delete the volume, and then recreate it.)
3. Reduce the physical volume size

I don't know if qtparted can do step 3 but it can do steps 1 and 2, I think.

Oh and of course, to do this, you must be running a separate copy of Linux
- like a live CD. Knoppix, for example, boots with usually no user intervention required, and contains qtparted and everything it needs.

My Reply

My Reply:
==============
Knoppix 3.7(whether you boot in 2.4 or 2.6 kernel) does not have lvm utilities or ext2resize binaries, so i tried to install over from internet but somehow i was not able to connect to default ftp.de.debian.org through "apt-get update", and to change source one must edit /etc/apt/source.list which i am not able to edit it as the file is only read-only.

Anyway i booted the system in linux resuce mode with FC3 rescue CD. I said not to mount any file system(not even read only) when asked during booting. Now first you need to activate the Volume Group, so you need to do.

# lvm vgchange -ay

then to reduce the file system(in my case it is root file system of ext3 type) in the activated volume group, first you need to run,

"e2fsck -v -f LogicalVolumeWithFullPath" in my case it was,

# e2fsck -v -f /dev/VolGroup00/LogVol00

then resize it with

# resize2fs -p /dev/VolGroup00/LogVol00 6G 
Resizes the ext3 file system in LogVol00 to 6GB.

Now after that When i check Logical Volumes with

# lvm lvdisplay 
i get

--- Logical volume ---

  LV Name                /dev/VolGroup00/LogVol00
  VG Name                VolGroup00
  LV UUID                6WyF9L-t4dJ-8HrR-NdTo-CoZh-NKvl-z6fidr
  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     0
  Block device           253:0

--- Logical volume ---

  LV Name                /dev/VolGroup00/LogVol01
  VG Name                VolGroup00
  LV UUID                N3auhB-e9br-76Cw-Eqvw-c31w-mq3Y-T5QBp8
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.00 GB
  Current LE             32
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:1

So here i can see that LogVol00 is reduces to 6GB as i wanted. and

# lvm vgdisplay 
shows,

VG Name VolGroup00
System ID

  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  12
  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               8.31 GB
  PE Size               32.00 MB
  Total PE              266
  Alloc PE / Size       224 / 7.00 GB
  Free  PE / Size       42 / 1.31 GB
  VG UUID               cdEPbO-5o71-hUIa-szPC-FAra-E79P-cdbuTS

But it still shows it as 8.31GB which is like before, but it shows that 42 PEs are free.

But now the problem is how to claim those 42 PEs from this Volume Group as i want to use that free space of this Volume Group to make hda7(fat32)
which i can use(read/write)both in linux as well as in windows.

Do i have to do as Robin Suggested that,

Can some one guide me step by step how to do it either from running FC3 itself or from rescue CD of FC3 or from Knoppix 3.7

is there any command in lvm2 to do this, i tried

# lvm pvresize 
but it said command not implemented yet. so how to do it?

Waiting for answers.

-ajeet.

You can't just shrink a PV like that AFAIK.

What you are asking is pretty much voodoo. Remember the solution that works every time is to back everything up to a tape or another harddrive, then setup the disk the way you want it and copy everything back. Trying to attempt voodoo as a self-admitted newbie is a sure-fire way to end up with complete loss of data on a system.

The LVM was designed to avoid these problems; however it is not designed to play well with other operating systems on the same box. So, you are stuck with native partitioning and all the problems that go along with it.

It is possible to do a lot of things by making more physical volumes, and using "pvmove" to move the logical volumes between disks. Once `pvdisplay -v' on a volume shows no data there you can safely repartition the space (and probably reboot each time), but from the sounds of it, you should not experiment with this approach. It is very easy to make a mistake and lose everything.

Sam Vilain, sam /\T vilain |><>T net, PGP key ID: 0x05B52F13
(include my PGP key ID in personal replies to avoid spam filtering)