Author Archives: BackTrack

Online resize LVM partitions – shrink home / extend root

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By default, most Linux Installers create separate /home partition, occupying most of the drive space.
When server is used mostly for system services, you may transfer free space from /home partition to /root.

Before adjustment we have 98% filled root partition and 141GB free space on /home, which we would like to use:
[code]
[root@oracle ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_oracle-lv_root
50G 1G 50G 98% /
tmpfs 630M 0 630M 0% /dev/shm
/dev/cciss/c0d0p1 477M 106M 346M 24% /boot
/dev/mapper/vg_oracle-lv_home
149G 60M 141G 1% /home
[/code]

1. First step is to unmount /home partition
[code]
umount /home
[/code]
System may refuse to unmount /home if you have users logged on to the box or services running from /home. After logging off / stopping services command should succeed.

2. Shrink old /home partition to 20GB, (system will force you to check filesystem for errors by running e2fsck)
[code]
e2fsck -f /dev/mapper/vg_oracle-lv_home
resize2fs /dev/mapper/vg_oracle-lv_home 20G
[/code]

3. Reduce the LVM to 20G
[code]
lvreduce -L 20G /dev/mapper/vg_oracle-lv_home
[/code]

4. Extend /root LVM to new size, utilizing 100% of free space on disk
[code]
lvextend -l +100%FREE /dev/mapper/vg_oracle-lv_root
[/code]

5. Grow /root (ext3/4) partition to new LVM size
[code]
resize2fs /dev/mapper/vg_oracle-lv_root
[/code]

6. Mount /home
[code]
mount /home
[/code]

Result
[code]
[root@oracle ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_oracle-lv_root
178G 50G 128G 28% /
tmpfs 630M 0 630M 0% /dev/shm
/dev/cciss/c0d0p1 477M 106M 346M 24% /boot
/dev/mapper/vg_oracle-lv_home
20G 45M 19G 1% /home

[/code]

After these simple steps we have 72% of free disk space of root partition.

TL;DR

Resizing /home partition (/dev/mapper/vg_oracle-lv_home) to 20GB and transfering remaining space to /root (/dev/mapper/vg_oracle-lv_root):

[code]
umount /home
e2fsck -f /dev/mapper/vg_oracle-lv_home
resize2fs /dev/mapper/vg_oracle-lv_home 20G
lvreduce -L 20G /dev/mapper/vg_oracle-lv_home
lvextend -l +100%FREE /dev/mapper/vg_oracle-lv_root
resize2fs /dev/mapper/vg_oracle-lv_root
mount /home
[/code]

Tags: , Posted by BackTrack in Linux on March 26, 2015
13 Replies

Apache error 500 after PHP upgrade

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When upgrading your server from old PHP release to 5.4 make sure your application does not use deprecated functions such as session_register.
This function may be used in older CMS versions, as Tiger CMS.

To comment out all occurrences of incompatible functions in the code you can use following command:
Example for session_register:

[code]
find . -type f -exec sed -i ‘s/session_register/\/\/session_register/g’ {} \;
[/code]

Generic troubleshooting steps for error 500 in Apache:

1. Check Apache error log
/var/log/apache2/error.log

2. Turn on PHP Error reporting in etc/php.ini (/etc/php5/apache2/php.ini)
[code]
error_reporting(E_ALL);
[/code]

3. Create an info.php file to test php, with content:

[code]

[/code]

So you can see what version you use and if it is loaded correctly.

Good Luck!

Tags: , Posted by BackTrack in Linux on February 4, 2015

Automating tasks with cron on CheckPoint Gaia

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To use cron on CheckPoint Gaia firewall you need to create a separate user, as “admin” user crontab file is overwritten on every reboot by /bin/cron_xlate.

Instead of using default command :
> crontab -e
It will warn you as follows:
[code]
# This file was AUTOMATICALLY GENERATED
# Generated by /bin/cron_xlate on Wed Jan 14 13:33:33 2015
#
# DO NOT EDIT
#
SHELL=/bin/bash
MAILTO=””
#
# mins hrs daysinm months daysinw command
#
[/code]

You will also need to specify the user:

> crontab -u cron_user -e

To create a new user for cron, use following commands:

[code]
add user cron_user uid 0 homedir /home/cron_user
set user cron_user gid 100 shell /bin/bash
add rba user cron_user roles adminRole
set user cron_user password
[/code]

Make sure you use new user’s home folder for output in your scripts, to avoid issues with permissions.

Tags: Posted by BackTrack in Other on January 14, 2015
1 Reply