Scenario: Configure 4 ethernet into 2 ethernet bond0 and bond1 on RHEL 6/CentOS 6.
System: RHEL 6.9
Steps:
1) Create new file bond0 (Eth0+Eth1) with IP Address = 172.16.10.70
# vi /etc/sysconfig/network-scripts/ifcfg-bond0
DEVICE=bond0
IPADDR=172.16.10.70
NETMASK=255.255.255.0
TYPE=Bond
ONBOOT=yes
NM_CONTROLLED=no
BOOTPROTO=none
USERCTL=no
PEERDNS=yes
IPV6INIT=no
Scenario:
Clone RHEL 6 VM template to NFS server using Clonezilla for deploy to physical server.
System included:
– Clonezilla iso.
– RHEL 6 VM Template.
– Windows server 2012 R2 NFS server.
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System: CentOS 6.9
Case:
Added new VM disk in CentOS 6 not showing the new VM disk when run fdisk -l.
Resolution:
Login as root, run this command to re-read the new VM disk without reboot the server.
ls /sys/class/scsi_host/ | while read host ; do echo "- - -" > /sys/class/scsi_host/$host/scan ; done
Example add below banner.
********************************************************************
* *
* This system is for the use of authorized users only. Usage of *
* this system may be monitored and recorded by system personnel. *
* *
* Unauthorized access to this machine is prohibited *
* Press Ctrl+D if you are not an authorized user *
* *
* Anyone using this system expressly consents to such monitoring *
* and is advised that if such monitoring reveals possible *
* evidence of criminal activity, system personnel may provide the *
* evidence from such monitoring to law enforcement officials. *
* *
********************************************************************
System: CentOS 6.9
Case:
– User request in ESXi to add new 30 GB VM disk(2nd disk it mean sdb) but accidentally wrong added VM disk only 10 GB,after remove the 10 Gb and added 30 GB when run fdisk -l still showing 10 GB VM disk size.
Resolution:
Login as root, run this command to re-read the new disk size without reboot the server.
# echo 1 > /sys/block/sdb/device/rescan
Scenario: How to increase or decrease swap space(logical volume swap) in CentOS 6/RHEL 6
System: CentOS 6/ RHEL 6
Steps increase Swap space
Example increase 1 GB swap space.
1) You must check the path of swap logical volume and the free space in the swap volume group before continue to step 2.
# free -m
# lvdisplay | grep swap
# vgs
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System: RHEL 6.9
Just got complain from App support Postfix was error.
Check on /var/log/maillog show this error
postfix[2319]: fatal: file /etc/postfix/main.cf: parameter default_privs: unknown user name value: nobody
The solution I did,check on /etc/passwd and found the user nobody in comment state.
Uncomment nobody and Postfix can start again.
# vi /etc/passwd
Uncomment nobody
# service postfix restart
Scenario: Install VMware-tools CentOS 6 on VMware ESXi 6
Steps:
– Right click on guest VM.
– Select Install/Upgrade VMware Tools. Note: VMware tools installer will assign as CD/DVD or iso image in the server.
– Login as root access the server or SSH remote to install VMware tools.
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Scenario:
Extend/Growing Logical Volume size for /opt on RHEL/CentOS 6.
Login as root then follow below steps:
1) Check free size in Volume Group (VolGroup).If still there free size then continue to step-2.
# vgs
[root@VTEST01 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 2 7 0 wz--n- 59.50g 12.00g
[root@VIDHOLXDTESTAP01 ~]#
Scenario:
Added new 10GB VMware Hard Disk,create new Volume Group(Vgs),Create new LVM,format to ext4 and mount to /data
Steps in VMware vSphere:
– Right click on VM -> Select Edit Settings… -> Click Add... -> on Device Type select Hard Disk -> Click Next
– Select Create a new virtual disk -> Click Next
– Specify disk size (this scenario is 10GB), select default Thick Provision Lazy Zeroed then specify the disk location (default is Store with virtual machine) -> Click Next
– Specify Virtual Device Node (default for 2nd Hard disk will be SCSI (0:1), on Mode box leave blank -> Click Next
– Click Finish.
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