Log into the VM through ssh or XenCenter. Next remove xs-tools with yum
yum remove -y `rpm -qa | grep xe-guest`
reboot the machine.
reboot
XenServer tools should now be removed.
Remove XenServer Tools from CentOS VM
Reply
Setup SNMP V3 on Zenoss
Before you start, make sure that you have SNMP V3 already setup on your device. You can refer to this post if you need to set it up.
Add the device to Zenoss, and then edit the devices Configuration Properties, you’ll need to configure the following settings.
Zenoss setting name Options
zSnmpSecurityName [user]
zSnmpPrivType (AES or DES)
zSnmpPrivPassword PASSPHRASE
zSnmpAuthType (MD5 or SHA)
zSnmpAuthPassword PASSPHRASE
zSnmpVer v3
After all the above changes are made, Zenoss should start graphing the device.
The chart below shows which snmpwalk options match which Zenoss Configuration Properties.
snmpwalk Zenoss Configuration snmpd.conf
-v zSnmpVers n/a
-u zSnmpSecurityName createUser [user]
-x zSnmpPrivType (AES or DES)
-X zSnmpPrivPassword PASSPHRASE
-a zSnmpAuthType (MD5 or SHA)
-A zSnmpAuthPassword PASSPHRASE
You can refer to the Zenoss wiki for more info.
Setting up SNMP V3 on CentOS
Install SNMP.
yum install net-snmp net-snmp-utils
Configure the SNMP V3 user by running the following command and then following the prompts it gives you.
net-snmp-create-v3-user
Example: The username is “snmpadmin” and the password is”r123456″
[root@localhost ~]# net-snmp-create-v3-user Enter a SNMPv3 user name to create: snmpadmin Enter authentication pass-phrase: r123456 Enter encryption pass-phrase: [press return to reuse the authentication pass-phrase] adding the following line to /var/lib/net-snmp/snmpd.conf: createUser snmpadmin MD5 "r123456" DES adding the following line to /etc/snmp/snmpd.conf: rwuser snmpadmin [root@localhost ~]#
Change the syslocation and syscontact in the /etc/snmp/snmpd.conf file.
vi /etc/snmp/snmpd.conf
Start snmpd service
service snmpd start
Configure snmp to start on system boot.
chkconfig snmpd on
Test and make sure snmp is working
replace “password” and “username” with the ones you setup when you created the SNMP V3 user.
snmpwalk -v3 -a MD5 -A password -x DES -X password -l authPriv -u privuser localhost
If you receive something like “snmpwalk: Timeout” then something is not working correctly. Check to make sure the service is started, and make sure that your firewall is not blocking SNMP.
If you are running a firewall, run the following commands to allow it through.
firewall-cmd --zone=public --add-port=161/udp --permanent semanage port -a -t snmp_port_t -p udp 161 firewall-cmd --reload
On iptables you should be able to do
iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 161 -j ACCEPT
or add it to /etc/sysconfig/iptables and then restart iptables
Increase hard disk size on Windows VM in XenServer
To increase a Windows VM disk size you’ll first need to shut down the VM and then increase the disk size from XenCenter. When you boot back up into the VM, the extra space shows up as unallocated. All that needs to be done is the main partition needs to be extended.
Open up the Windows Disk Management Utility. You can do this by clicking on the start button, typing in disk management and hit enter. This will bring up the Disk Management program.
In disk manager, you should see the Unallocated space at the end of Disk 0, i.e. your main drive. Right click on your main partition (C:) and click Extend Volume. You will be presented with a wizard that will walk you through extending your disk.
Example:
Before increasing the VM’s disk size.
The unallocated space is the extra space that we added via XenCenter. Right click on the middle partition (C:), and click extend.
After were are finished extending the partition, we see that our main partition is about 8GB larger.
How to setup a Planets3 Alpha Multiplayer Server
Prerequisite:
- Windows computer/server that has a public IP address
- Planets3Alpha downloaded to the above computer (The Server is included in the Windows Planets3 Alpha download)
Installing Planets3 Alpha
Installing Planets3 Alpha is easy to do. Run the installer and follow the prompts. The server gets installed when you install the Planets3 Alpha, you just have to launch the server file to run the server.
Setting up Firewall
Click on the Start button type in firewall and hit enter. This should start up the Windows Firewall application.
What we need to do is create a new inbound rule to allow UDP port 7777 (the Planets3 server port) so we can connect to the server.
Click on Inbound Rules, and then Create a New Rule…
Select Port.
Select “UDP” and “Specific local ports:” The port number is 7777
Give the New Rule a Name and Description. 
And finally click Finish.
Configure Planets3Alpha to Start on System Log In
You can manually launch the server by double clicking on the “start_server” file under “C:\Program Files (x86)\Planets3Alpha\”
If you want to have Planets3 Startup on system log in, do the following.
Open up the Planets3 install directory in Windows Explorer, it should be under “C:\Program Files (x86)\Planets3Alpha\”. Create a shortcut by right clicking on “start_server” then Create shortcut. Now drag the shortcut to the Startup folder found under All Programs in the start menu.
That’s it. You should be able to reboot, log in, and have Planets3 Alpha multiplayer server start automatically. All that is left is for you to connect to your new server.
How To Create a Clonezilla Boot Drive
- Format USB Drive as FAT32
- Download the Clonezilla Live zip here or from Clonzilla’s website.
- Extract the zip, and copy the contents to the root of your USB drive
- Run the appropriate version of makeboot. “H:\” is you usb drive. Change if necessary.
- 64bit is under “H:\utils\win64\makeboot64.bat”
- 32bit is under “H:\utils\win32\makeboot.bat”
- Make sure you are running makeboot.bat from the USB drive and NOT you local C: drive.
- Follow the prompts and when it is finished try to boot from it.
How to add extra space to Linux VM in XenServer
Before we start you will need to do the following in XenCenter
- Shutdown the VM
- Increase the virtual hard drive size of the Linux VM
- Boot the VM back up
Before starting any of the following, it is a good idea to backup any data you would not want to lose. You should not lose any data following these steps, but there is always the possibility for something to go wrong.
What is going to happen
- Delete the main partition. We are going to recreate it.
- Create a new partition that starts on the same boundary as the previous partition
- Write changes to disk and reboot
- Resize the Disk
- Check that everything went well
The path to the disk is “/dev/xvda” the LVM path/name is “/dev/VolGroup/lv_root” The goal is to increase lv_root’s size from about 8GB to about 12GB. If for some reason your drive is not “xvda” or your LVM name is different, change the commands accordingly.
Here are the commands in a nutshell.
fdisk /dev/xvda <-- Edit the Partition Table reboot <-- Reboot to apply the partition table updates pvdisplay <-- Display Physical Volume info pvresize /dev/xvda2 <-- Resize Physical Volume lvresize /dev/xvda2 -l +100%FREE <-- Resize Logical Volume resize2fs /dev/VolGroup/lv_root <-- Resize File System
Example:
You may be able to substitute all the fdisk commands with
`parted /dev/xvda resizepart 2 100%`
Change 2 for the actual partition you need to resize.
All the keys and command that were hit and executed are in bold.
[root@localhost ~]# fdisk /dev/xvda WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). Command (m for help): p Disk /dev/xvda: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 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: 0x00066ace Device Boot Start End Blocks Id System /dev/xvda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/xvda2 64 1045 7875584 8e Linux LVM Command (m for help): d Partition number (1-4): 2 Command (m for help): p Disk /dev/xvda: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 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: 0x00066ace Device Boot Start End Blocks Id System /dev/xvda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 2 First cylinder (64-1566, default 64): Command (m for help): p Disk /dev/xvda: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 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: 0x00066ace Device Boot Start End Blocks Id System /dev/xvda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/xvda2 64 1566 12065871 83 Linux Command (m for help): wq The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks. [root@localhost ~]# reboot
Show the current size of the Physical Volume
pvdisplay
[root@localhost ~]# pvdisplay --- Physical volume --- PV Name /dev/xvda2 VG Name VolGroup PV Size 7.51 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 1922 Free PE 0 Allocated PE 1922 PV UUID zKmGEt-Uf0A-I14h-NDYc-53rf-micT-VxNqsP [root@localhost ~]#
Resize the Physical Volume
pvresize /dev/xvda2
[root@localhost ~]# pvresize /dev/xvda2 Physical volume "/dev/xvda2" changed 1 physical volume(s) resized / 0 physical volume(s) not resized [root@localhost ~]#
Run pvdisplay again. You should see more space under PV Size.
[root@localhost ~]# pvdisplay --- Physical volume --- PV Name /dev/xvda2 VG Name VolGroup PV Size 11.51 GiB / not usable 2.08 MiB Allocatable yes PE Size 4.00 MiB Total PE 2945 Free PE 1023 Allocated PE 1922 PV UUID zKmGEt-Uf0A-I14h-NDYc-53rf-micT-VxNqsP [root@localhost ~]#
Notice the “Free PE” section above. If it says 0 then you won’t be able to run the next command.
Resize LVM
the “+100%FREE” part of the command tells it to uses up all of the free space available
lvresize /dev/VolGroup/lv_root -l +100%FREE
[root@localhost ~]# lvresize /dev/VolGroup/lv_root -l +100%FREE Extending logical volume lv_root to 10.71 GiB Logical volume lv_root successfully resized [root@localhost ~]#
Resize the File System
resize2fs /dev/VolGroup/lv_root
[root@localhost ~]# lvresize /dev/VolGroup/lv_root -l +100%FREE Extending logical volume lv_root to 10.71 GiB Logical volume lv_root successfully resized [root@localhost ~]#
And that is it. Check out the extra space.
[root@localhost ~]# df -h / Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup-lv_root 11G 733M 9.3G 8% / [root@localhost ~]# exit
Create a Bootable OS X Yosemite Thumb Drive – Simple Version
Open up disk utility and format your thumb drive as “Mac OS Extended (Journaled)”
Open up a terminal, and run the following command. Change “USBdrive” to your USB Drives name.
sudo /Path/to/Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/USBdrive --applicationpath /Path/to/Yosemite.app --nointeraction
Enter in your password and let it run.
Example:
sudo /Applications/Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/OSXInstaller --applicationpath /Applications/Yosemite.app --nointeraction
How to Boot a XenServer VM into Recovery Mode
Recovery Mode can be helpful if you need to do certain task like operate on the VM with the disk unmounted or you need to reset a root password.
All of the following is done through XenCenter
To boot the VM into recovery mode all you have to do is
- Shutdown the VM
- Insert boot media i.e. (DVD, cd, iso image, etc.) into DVD Drive 1:
- Start VM in Recovery Mode. In the main menu click on VM –> Start/Shut Down –> Start in Recovery Mode
When the VM boots up it will boot off of whatever is in DVD Drive 1.
How to Backup and Restore UniFi data from the Command Line
Backup
backup the UniFi directory
tar zcvf unifi-backup.tgz /usr/UniFi/
Move the tar archive off site.
Restore
Upload the backup file to the server.
Note: You will need to have the UniFi controller install already.
Copy the archive to the root directory and then extract it.
mv unifi-backup.tgz / cd / tar zxvf unifi-backup.tgz
Reboot the server and login to the UniFi controller.
reboot