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vzdump: create KVM backups with an specific name

January 24, 2012January 24, 2012 sysadmin Leave a comment

With Proxmox VE, the virtual environment I am using, you can configure KVM backups, but you are going to get dump files like this:

vzdump-qemu-117-YYYY_MM_DD-HH_MM_SS.tgz

The names of these files are not very representative and you should rename them if you want to easily identify your KVM backups in your storage.

I am using this command for KVM backups to get the files with their server names:

#
# vzdump --compress  --snapshot --storage pve-backups --maxfiles 2 --stdout 117 > /mnt/pve/pve-backups/myserver_YYYY_MM_DD.tgz
#

You can put this command in a cron if you want.

To restore the machine simply run:

#
# qmrestore /mnt/pve/pve-backups/myserver_YYYY_MM_DD.tgz 117
#

VLAN tagging on Linux for KVM

January 10, 2012January 10, 2012 sysadmin Leave a comment

Today, I’m going to explain my config for KVM server to get network connectivity on guests machines using tagged vlans to get independent networks. As virtual platform I am using Proxmox ve. Proxmox is a great platform to administer KVM and OpenVZ machines, actually it is based on Debian Lenny, but very soon will be available the 2.0 version based on Debian Squeeze and with many great features.

I have connected my kvm server network interfaces to two different switches and the switch ports configured in trunk mode only accepting traffic for my tagged vlans. For vlan configuration I am using vlan package in debian, rather than specify them like eth0.X, I prefer to configure them using this tool.

To install vlan package simply run:

 # apt-get install vlan

Above the two network interfaces I have configured a bond interface in active-backup mode. My /etc/network/interfaces file looks like this:

iface eth0 inet manual
iface eth1 inet manual


auto bond0
iface bond0 inet manual
        slaves eth0 eth1
        bond_miimon 100
        bond_mode active-backup

auto vlan50
iface vlan50 inet manual
        vlan_raw_device bond0

auto vlan60
iface vlan60 inet manual
       vlan_raw_device bond0

auto vlan100
iface vlan100 inet manual
       vlan_raw_device bond0


auto vmbr0
iface vmbr0 inet static
        address  172.17.16.5
        netmask  255.255.240.0
        gateway  172.17.16.1
        bridge_ports vlan100
        bridge_stp off
        bridge_fd 0

auto vmbr50
iface vmbr50 inet static
        address 0.0.0.0
        netmask 255.255.255.255
        bridge_ports vlan50
        bridge_stp off
        bridge_fd 0

auto vmbr60
iface vmbr60 inet static
        address 0.0.0.0
        netmask 255.255.255.255
        bridge_ports vlan60
        bridge_stp off
        bridge_fd 0

I have three bridges configured, vmbr0 (with vlan 100), required to access proxmox web interface, and vmbr50 and vmbr60, each of them accessing to their vlans to provide access to guests. The bridge vmbr0 is the only bridge that has an IP address configured, because is the only interface I’m going to use to access to the kvm server.

Now, it is easy to provide network connectivity to the kvm guests machines, simply you have to link their network interfaces to the bridge you want depending on, to that vlan you want they get access.

For example, part of one of my kvm machine config file looks like this:


vlan60: virtio=DE:17:7C:C3:CE:B2
vlan50: virtio=B2:0A:19:3E:72:4D

This is automatically added using proxmox ve web interface.

Rename linux network interfaces

January 9, 2012January 10, 2012 sysadmin Leave a comment

Sometimes it can be useful to have network interfaces with an recognizable name, rather than eth0, eth1,… with which you can easily identify to which networks they are connected. For example, if you have a server connected to many networks and vlans you can identify the network/vlan based on interface name, eth50 for vlan50, eth100 for vlan100,… or you can simply rename interface to vlan50, vlan100 directly.

In Debian you should install ifrename package and create the file /etc/iftab with this format:

$ cat /etc/iftab 
eth50  mac F2:A8:C0:77:82:94
eth55  mac 4E:DF:22:FD:71:EA

In Redhat/CentOS you can rename /etc/sysconfig/network-scripts/ifcfg-eth0 to /etc/sysconfig/network-scripts/ifcfg-XXXX and edit file specifying this name. For example, I have my ifcfg-eth50 script like this:

DEVICE=eth50 NM_CONTROLLED=yes ONBOOT=yes HWADDR=9c:83:4f:af:a1:ec TYPE=Ethernet BOOTPROTO=none IPADDR=172.16.0.19 PREFIX=23 DEFROUTE=yes IPV4_FAILURE_FATAL=yes IPV6INIT=no NAME=eth50 UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 NETMASK=255.255.254.0 USERCTL=no

In Ubuntu, I did not try it but I think you can edit the file /etc/udev/rules.d/70-persistent-net.rules and change the name of interface according to its mac address.

Access denied for user ‘debian-sys-maint’@’localhost’ (using password: YES)

August 24, 2011August 24, 2011 sysadmin Leave a comment

I had this error when I moved all database server files, phisically, from one server to another for replication purposes and used the mysql startup script. The new server is a Debian Squeeze, in debian there is a user debian-sys-maint to do maintenance tasks, to avoid this error with the mysql startup script you have to create this user in your new database server.

The password for this user can be seen in this file:

# cat /etc/mysql/debian.cnf

# Automatically generated for Debian scripts. DO NOT TOUCH!
[client] host = localhost
user = debian-sys-maint
password = password
socket = /var/run/mysqld/mysqld.sock
[mysql_upgrade] host = localhost
user = debian-sys-maint
password = password
socket = /var/run/mysqld/mysqld.sock
basedir = /usr

To create the user, log in as mysql root user and run this statement:

GRANT ALL PRIVILEGES ON *.* TO 'debian-sys-maint'@'localhost' IDENTIFIED BY 'password';

In my case, the original server was a Centos 5.5, so that the user debian-sys-maint did not exist, but in case the server was another Debian you can use the same statement to only reset the user password.

How to resize KVM virtual machine disk file

August 22, 2011September 14, 2011 sysadmin Leave a comment

In KVM when you create a new virtual machine, you have to specify the initial size of the disk that the machine is going to use. If later, you realize that initial size is not enough, you can resize disk image with qemu-img command:

$ qemu-img resize vm-101-disk-1.raw +10G

In the example we have resized the disk image with 10Gb more. The new size can be specified in K for kilobyte, M for megabyte and G for gigabyte.

Inside virtual machine you are going to see new unassigned free space in the disk. If we have partitioned the guest machine with LVM we can easily extend the logical volumes with the new space we have newly created in the disk. To do that we only have to create a new LVM partition and assign the new partition to the existing volume group.