add note about unique cluster names

[pve-docs.git] / sysadmin.adoc

Host System Administration
==========================
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{pve} is based on the famous https://www.debian.org/[Debian] Linux
distribution. That means that you have access to the whole world of
Debian packages, and the base system is well documented. The
https://debian-handbook.info/download/stable/debian-handbook.pdf[Debian
Administrator\'s Handbook] is available online, and provides a
comprehensive introduction to the Debian operating system (see
xref:Hertzog13[]).

A standard {pve} installation uses the default repositories from
Debian, so you get bug fixes and security updates through that
channel. In addition, we provide our own package repository to roll
out all {pve} related packages. This includes updates to some
Debian packages when necessary.

We also deliver a specially optimized Linux kernel, where we enable all
required virtualization and container features. That kernel includes
drivers for http://zfsonlinux.org/[ZFS], and several hardware drivers.
For example, we ship Intel network card drivers to support their
newest hardware.

The following sections will concentrate on virtualization related
topics. They either explains things which are different on {pve}, or
tasks which are commonly used on {pve}. For other topics, please refer
to the standard Debian documentation.

System requirements
-------------------

For production servers, high quality server equipment is needed. Keep
in mind, if you run 10 Virtual Servers on one machine and you then
experience a hardware failure, 10 services are lost. {pve}
supports clustering, this means that multiple {pve} installations
can be centrally managed thanks to the included cluster functionality.

{pve} can use local storage (DAS), SAN, NAS and also distributed
storage (Ceph RBD). For details see xref:chapter-storage[chapter storage].

Minimum requirements, for evaluation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* CPU: 64bit (Intel EMT64 or AMD64)

* RAM: 1 GB RAM

* Hard drive

* One NIC

Recommended system requirements
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* CPU: 64bit (Intel EMT64 or AMD64), Multi core CPU recommended

* RAM: 8 GB is good, more is better

* Hardware RAID with batteries protected write cache (BBU) or flash
 based protection

* Fast hard drives, best results with 15k rpm SAS, Raid10

* At least two NIC´s, depending on the used storage technology you need more


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Network Configuration
---------------------

{pve} uses a bridged networking model. Each host can have up to 4094
bridges. Bridges are like physical network switches implemented in
software. All VMs can share a single bridge, as if
virtual network cables from each guest were all plugged into the same
switch. But you can also create multiple bridges to separate network
domains.

For connecting VMs to the outside world, bridges are attached to
physical network cards. For further flexibility, you can configure
VLANs (IEEE 802.1q) and network bonding, also known as "link
aggregation". That way it is possible to build complex and flexible
virtual networks.

Debian traditionally uses the 'ifup' and 'ifdown' commands to
configure the network. The file '/etc/network/interfaces' contains the
whole network setup. Please refer to to manual page ('man interfaces')
for a complete format description.

NOTE: {pve} does not write changes directly to
'/etc/network/interfaces'. Instead, we write into a temporary file
called '/etc/network/interfaces.new', and commit those changes when
you reboot the node.

It is worth mentioning that you can directly edit the configuration
file. All {pve} tools tries hard to keep such direct user
modifications. Using the GUI is still preferable, because it
protect you from errors.

Naming Conventions
~~~~~~~~~~~~~~~~~~

We currently use the following naming conventions for device names:

* Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...)

* Bridge names: vmbr[N], where 0 ≤ N ≤ 4094 (`vmbr0` - `vmbr4094`)

* Bonds: bond[N], where 0 ≤ N (`bond0`, `bond1`, ...)

* VLANs: Simply add the VLAN number to the device name,
  separated by a period (`eth0.50`, `bond1.30`)

This makes it easier to debug networks problems, because the device
names implies the device type.

Default Configuration using a Bridge
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The installation program creates a single bridge named `vmbr0`, which
is connected to the first ethernet card `eth0`. The corresponding
configuration in '/etc/network/interfaces' looks like this:

----
auto lo
iface lo inet loopback

iface eth0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.10.2
        netmask 255.255.255.0
        gateway 192.168.10.1
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
----

Virtual machines behave as if they were directly connected to the
physical network. The network, in turn, sees each virtual machine as
having its own MAC, even though there is only one network cable
connecting all of these VMs to the network.


Routed Configuration
~~~~~~~~~~~~~~~~~~~~

Most hosting providers do not support the above setup. For security
reasons, they disable networking as soon as they detect multiple MAC
addresses on a single interface.

TIP: Some providers allows you to register additional MACs on there
management interface. This avoids the problem, but is clumsy to
configure because you need to register a MAC for each of your VMs.

You can avoid the problem by "routing" all traffic via a single
interface. This makes sure that all network packets use the same MAC
address.

A common scenario is that you have a public IP (assume 192.168.10.2
for this example), and an additional IP block for your VMs
(10.10.10.1/255.255.255.0). We recommend the following setup for such
situations:

----
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
        address  192.168.10.2
        netmask  255.255.255.0
        gateway  192.168.10.1
        post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp


auto vmbr0
iface vmbr0 inet static
        address  10.10.10.1
        netmask  255.255.255.0
        bridge_ports none
        bridge_stp off
        bridge_fd 0
----


Masquerading (NAT) with iptables
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In some cases you may want to use private IPs behind your Proxmox
host's true IP, and masquerade the traffic using NAT:

----
auto lo
iface lo inet loopback

auto eth0
#real IP adress 
iface eth0 inet static
        address  192.168.10.2
        netmask  255.255.255.0
        gateway  192.168.10.1

auto vmbr0
#private sub network
iface vmbr0 inet static
        address  10.10.10.1
        netmask  255.255.255.0
        bridge_ports none
        bridge_stp off
        bridge_fd 0

        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up   iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
----

////
TODO: explain IPv6 support?
TODO: explan OVS
////


////
TODO:

Local Storage
-------------

Logical Volume Manager (LVM)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TODO: info about LVM.


ZFS on Linux
~~~~~~~~~~~~

TODO: info about ZFS.


Working with 'systemd'
----------------------

Journal and syslog
~~~~~~~~~~~~~~~~~~

TODO: explain persistent journal...


////