How to create file systems at run time

rahulmishra1312 · 04-16-2009, 01:01 AM

Hi,

I've only a root file system of 100 GB on my Red Hat Linux PC.
Now I want it to break down into 2 or more file systems. Can it be done at run time, If yes then what are the steps for doing so.

Thanks
Rahul

kirukan · 04-16-2009, 01:32 AM

Filesystem means a method for storing and organizing computer files and the data(windows using NTFS & FAT, Linux using ext2 & ext3) here you want to partation your disk. try with gparted it may be helpful
http://gparted.sourceforge.net/

theYinYeti · 04-16-2009, 01:41 AM

You cannot do this live. But offline, gparted should indeed be able to do what you want. Don't forget to do backups.

Yves.

Disillusionist · 04-16-2009, 01:50 AM

It depends on your Red Hat installation, if you chose to use LVM when you installed Red Hat, then you can reduce the size of the partition whilst it is running (although I would ensure I had a clean backup before making the attempt). You could then create a new partition on the free space.

This is possible because the disk is allocated to LVM and LVM is changing how it's utilising the disk.

I don't believe you should use Gparted or other methods of changing partition size (fdisk) if you are using LVM.

EDIT: Cannot reduce whilst running only increase

theYinYeti · 04-16-2009, 02:22 AM

Disillusionist is right about LVM. However, to my knowledge, it doesn't apply to the “/” (aka. root) partition. Besides, although resizing partitions in a live system is possible, I don't know of a filesystem that allows resizing while mounted (hence the “/” restriction).

Yves.

Disillusionist · 04-16-2009, 02:28 AM

I have resized mounted partitions on RHEL with LVM (even when being actively used), although I have never tried on the / partition.

theYinYeti · 04-17-2009, 01:50 AM

That is good news! How did you do that, and with what filesystem?

Yves.

chrism01 · 04-17-2009, 01:58 AM

To do a reduce on an LVM / ext3 system

Code:

df -h /data
umount /data
e2fsck -f /dev/vg0/data
resize2fs /dev/vg0/data 128M
lvreduce -L 128M /dev/vg0/data
mount /dev/vg0/data /data
df h /data

Always take 1+ backups before starting and try not to be using that fs.
Might not work on '/', you'd probably reboot & use 'linux rescue' mode from the install DVD; should be mounted under /mnt/sysimage

Disillusionist · 04-17-2009, 11:17 AM

Quote:

Originally Posted by theYinYeti

That is good news! How did you do that, and with what filesystem?

Yves.

You can increase the size of a logical volume whilst it is mounted, what you can't do is decrease the size whilst it is mounted

On RHEL (same for CentOS) go into system-config-lvm

Select the volume to be modified, and click Edit Properties.

Set the new size and click OK

If you are reducing the size, you will be told that the filesystem needs to be unmounted and asked if it's ok to unmount the filesystem and continue, if you are increasing it will just continue.

Just tested and increased size of / on the fly

You can even run df -k on the mount point and watch as the size is increased