[SOLVED] How to increase size of my / root partition

Nick_C · 04-03-2016, 12:14 PM

Running CentOS 6.3 and need to expand the root partition into the unused space next to it?

Tried booting into single user mode but gparted still doesn't allow the (mounted) root partition to be expanded.

Can boot from CD to CentOS 7 systemrescue but from there how do I change the size of the partition.

Unfortunately this old server doesn't seem to like running from any of the live environments (Fedora Live locks-up) which rules out doing it from within any of the live linux distros.

Any suggestions?

michaelk · 04-03-2016, 03:39 PM

Need some additional information.

How is your drive currently partitioned? Post the output of the command (as root)
fdisk -l (that is a small L)

Are you using LVM?

John VV · 04-03-2016, 05:48 PM

back up all your data
reinstall with 6.7
6.3 has not been supported for a few years

i am guessing you are not using a LVM ( the DEFAULT setting )
that you might be able to resize ? maybe ?

what is the output of

Code:

fdisk -l

X-LFS-2010 · 04-03-2016, 08:08 PM

carefully!

you can move files not needed to boot out of (p1) and make them mounts (there is a new option called "bind" too). there are partition moving programs (they are rhobust but you should back up). if you use raid (or which type of filesystem) is an issue. if you have ext2 its simple failsafe and fast - your probably ok. use some highly featured complex filesystem: it might buck and twist and loose something.

however: the BEST thing to do is

1) back up

2) make two partitions, #1 for rescue (a full but more minimal install), #2 the whole system

also important: your "/" keeps a record of all mounts of all kinds. if you change "/" and the mounts "aren't there yet" your system will no longer be coherent and no longer work.

finally, each chroot/ directory is it's own "/", and once (root user) is in it the (user) has the same full access to the kernel as "the real /", so security is out the window on most of todays systems (unless very carefully assembled).

if you can copy sys files into chroot then type "chroot chroot1/" then it's a chroot, just one of any number of "/" the kernel sees

good luck

Nick_C · 04-04-2016, 05:53 AM

Output from fdisk -l

Code:

[root@Storage1]# fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00056923

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1936    15549896   83  Linux
/dev/sda4            5585       38913   267715192+   f  W95 Ext'd (LBA)
/dev/sda5           38411       38913     4040316   82  Linux swap / Solaris
/dev/sda6            5585       38410   263674782   83  Linux

Partition table entries are not in disk order

michaelk · 04-04-2016, 06:45 AM

gparted does have a live CD/USB image. Make sure you backup any and all important data just in case. Hopefully they are small enough to run on your system.

http://gparted.sourceforge.net/livecd.php
or
http://www.system-rescue-cd.org/SystemRescueCd_Homepage

Nick_C · 04-04-2016, 01:12 PM

Is there no way or resizing the partition from the command line?

rknichols · 04-04-2016, 02:00 PM

Yes, but you have to get things exactly right or your machine won't boot and you'll need to boot from something like SystemRescueCD to recover. If you aren't already familiar with the command line partitioning tools, I don't recommend that you try. Just boot from the rescue CD that you're likely to need anyway and run gparted from that.

If you're really insistent on doing it from the command line on the running system, post the output from "fdisk -lu" so that I can see exactly how to proceed or whether you're going to run up against the limitations fdisk has about where the first partition can start. You're using an old version of fdisk that defaults to cylinder units, and that's not exact enough.

Nick_C · 04-04-2016, 03:55 PM

fdisk -lu returns:

Code:

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00056923

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048    31101839    15549896   83  Linux
/dev/sda4        89706960   625137344   267715192+   f  W95 Ext'd (LBA)
/dev/sda5       617056713   625137344     4040316   82  Linux swap / Solaris
/dev/sda6        89707086   617056649   263674782   83  Linux


Partition table entries are not in disk order

I don't need to do this from a running system as I can boot from CD to CentOS 7 SystemRescue. Just checked and I am actually running version 6.7.

BW-userx · 04-04-2016, 05:34 PM

Quote:

Originally Posted by Nick_C

Is there no way or resizing the partition from the command line?

you got something against Gparted? that'd be the way I'd go, and have done so.

rknichols · 04-04-2016, 06:48 PM

The easiest command line tool to make this change is sfdisk. First, use sfdisk to dump the current partitioning onto a file:

Code:

sfdisk -d /dev/sda >parts.out

The contents of the file will look like this:

Code:

# partition table of /dev/sda
unit: sectors

/dev/sda1 : start=     2048, size= 31099792, Id=83
/dev/sda2 : start=        0, size=        0, Id= 0
/dev/sda3 : start=        0, size=        0, Id= 0
/dev/sda4 : start= 89706960, size=535430385, Id= f
/dev/sda5 : start=617056713, size=  8080632, Id=82
/dev/sda6 : start= 89707086, size=527349564, Id=83

Edit that file and make the size for partition 1 larger. The maximum that will fit in the available space is 89704912 sectors. That would increase the partition size from its current ~15GB to ~44GB.

Code:

# partition table of /dev/sda
unit: sectors

/dev/sda1 : start=     2048, size= 89704912, Id=83
/dev/sda2 : start=        0, size=        0, Id= 0
/dev/sda3 : start=        0, size=        0, Id= 0
/dev/sda4 : start= 89706960, size=535430385, Id= f
/dev/sda5 : start=617056713, size=  8080632, Id=82
/dev/sda6 : start= 89707086, size=527349564, Id=83

Now use sfdisk to repartition /dev/sda from that file and then enlarge the filesystem to fill its new partition:

Code:

sfdisk /dev/sda <parts.out
resize2fs /dev/sda1

Really, you can do all that from the running system. You will just have to include the "--force" option with sfdisk in the repartitioning step and then reboot before resizing the filesystem. The only issue with that is that "--force" will also override any other detectable problems.

(I'm really hesitating before hitting "Submit Reply" on this, but here goes ...)

sundialsvcs · 04-04-2016, 07:17 PM

Easily the best thing to do is to convert the system to use LVM = Logical Volume Management. If this had already been in place, then you could have simply added another "physical volume" to the root "storage pool."

CGIMan · 04-04-2016, 09:51 PM

Resizing volumes is a breeze with LVM and it can be done using the command line since Nick_C is interested in the CLI.

Plus, you can set a volume for doing snapshots for system restore and/or recovering deleted files depending on which volume you're snapshoting.

Nick_C · 04-05-2016, 12:11 PM

Quote:

Originally Posted by rknichols

The easiest command line tool to make this change is sfdisk...

Thanks rknichols, worked perfectly. What I actually did for safety was boot to the CentOS 7 SystemRescue prompt and did the resizing from there.

Job done partition is now 30Gb, many thanks.