Extending root Partition

bk4linux · 03-04-2020, 12:30 PM

Hi all;
Newbie here, but able to find my way around Linux system.
OS is CentOS7.
How do I extend the system root (/) partition? / has 100%,
First of all, what can I safely delete to relief pressure on the system before going for the disk expansion?
Many thanks

John VV · 03-04-2020, 12:36 PM

first thing is to remove all files in /tmp

then remove old log files in " /var/log/"

that should free up some space

teckk · 03-04-2020, 12:50 PM

You can move the end of the last partition on a drive.

So if you were to have on /dev/sda

Code:

/dev/sda1    /   1GB
/dev/sda2    /home   20GB
free space  100GB

You could move the end of sda2 into the free space, then extend the file system on sda2 to fill the new partition size.

If you wanted to enlarge /dev/sda1

You'll have to delete /dev/sda2

Move the end of /dev/sda1 where you want it, extend the file system on it

Then remake /dev/sda2, format it, put your stuff back on it.

kilgoretrout · 03-04-2020, 01:30 PM

It depends on the filesystems involved and the partition layout neither of which you have provided.

uteck · 03-04-2020, 02:13 PM

You may want to look at bootable Linux with a graphical partition manager to do this with like https://gparted.org/livecd.php
As with any file system, backup everything and assume you will mess up. If you do mess up, try to learn what you did wrong. It's the best way to learn.

It should be possible to shrink a partition to make free space if none is available, then expand / provided the free space is next to it.

michaelk · 03-04-2020, 03:12 PM

Welcome to LinuxQuestions.

By default CentOS 7 uses LVM and xfs filesystems. As kilgoretrout posted it depends on how your system was configured with one caveat that xfs filesystems can only be enlarged not reduced.

bk4linux · 03-04-2020, 04:02 PM

I rebooted the server due to other factors and now I can not log in again. I'm getting this error... "authentication service cannot retrieve authentication info"

teckk · 03-04-2020, 04:47 PM

Sorry wrong thread

uteck · 03-04-2020, 05:31 PM

Can you reboot into recovery mode from the grub menu, or single user mode?
You first posted that / was at 100%, so if it is still like that, then it seems there no space to login. Recover mode should not start some services, so might leave some space on / to run some commands.

agillator · 03-04-2020, 08:52 PM

You might try booting with a live disk (your installation disk?) and then mounting your partition somewhere. Even if it is really full you should be able to mount it. Then do as others have suggested on removing files. Also do a search for any .Trash or variations directories and lost+found although you probably won't find the latter unless you normally have external mounts. Files in either are safe to delete. Note you need to actually remove them (rm xxxxx) not send to trash through file manager. Then look at the drive with fdisk or parted or the equivalent and see if the partition can be enlarged considering michaelk's post.

bk4linux · 03-05-2020, 10:15 AM

I have booted the system with CentOS ISO image and can access the /root on /mnt/sysimage. I was able to remove bunch of files from /tmp and /var/logs/.
However, I wanted to create a user account with root level permission to help me gain access into the system to troubleshoot the new error …"authentication service cannot retrieve authentication info"
The background info is that, I inherited this from another sysadmin that left. All I have is a single AD domain based account. No info on the local admin or root account.
So now that I have the opportunity to bring the system to a single user mode, I will like to have a normal local admin account to help in future troubleshooting.

I have tried useradd myadm ; passwd myadm xxxxx but it doesn't seem to be working.
Any idea how to create a root level account in single user mode?

Thanks in advance.

teckk · 03-05-2020, 12:34 PM

Quote:

All I have is a single AD domain based account. No info on the local admin or root account.

If you are going to be admin then you need that.
https://www.liberiangeek.net/2014/09...tos-7-servers/

https://wiki.centos.org/Documentation
https://wiki.centos.org/FAQ/CentOS7
https://wiki.centos.org/HowTos

bk4linux · 03-05-2020, 12:46 PM

Quote:

Originally Posted by bk4linux

I have booted the system with CentOS ISO image and can access the /root on /mnt/sysimage. I was able to remove bunch of files from /tmp and /var/logs/.
However, I wanted to create a user account with root level permission to help me gain access into the system to troubleshoot the new error …"authentication service cannot retrieve authentication info"
The background info is that, I inherited this from another sysadmin that left. All I have is a single AD domain based account. No info on the local admin or root account.
So now that I have the opportunity to bring the system to a single user mode, I will like to have a normal local admin account to help in future troubleshooting.

I have tried useradd myadm ; passwd myadm xxxxx but it doesn't seem to be working.
Any idea how to create a root level account in single user mode?

Thanks in advance.

I've fixed this by booting into Linux Rescue, mount root fs to /mnt/sysimage, chroot /mnt/sysimage, change root psw passwd root. Type exit before rebooting. Then finally was able to login locally with the root account and new password.

Now back to my original issue of "How to extend /root partition" that is at 100%. I'm running lvm. Please I still need help on this. Thanks all

teckk · 03-05-2020, 12:56 PM

Google, read the docs, normal fs look at post #3.

lvm
https://www.tecmint.com/extend-and-r...lvms-in-linux/
https://webhostinggeeks.com/howto/cr...-linux-centos/
https://www.techbrown.com/linux-lvm-...lume-centos-7/
https://unix.stackexchange.com/quest...-lvm-partition