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495 lines
18 KiB
ReStructuredText
495 lines
18 KiB
ReStructuredText
=================================
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Network Configuration Reference
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=================================
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Network configuration is critical for building a high performance :term:`Ceph
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Storage Cluster`. The Ceph Storage Cluster does not perform request routing or
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dispatching on behalf of the :term:`Ceph Client`. Instead, Ceph Clients make
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requests directly to Ceph OSD Daemons. Ceph OSD Daemons perform data replication
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on behalf of Ceph Clients, which means replication and other factors impose
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additional loads on Ceph Storage Cluster networks.
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Our Quick Start configurations provide a trivial `Ceph configuration file`_ that
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sets monitor IP addresses and daemon host names only. Unless you specify a
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cluster network, Ceph assumes a single "public" network. Ceph functions just
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fine with a public network only, but you may see significant performance
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improvement with a second "cluster" network in a large cluster.
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We recommend running a Ceph Storage Cluster with two networks: a public
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(front-side) network and a cluster (back-side) network. To support two networks,
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each :term:`Ceph Node` will need to have more than one NIC. See `Hardware
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Recommendations - Networks`_ for additional details.
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.. ditaa::
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+-------------+
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| Ceph Client |
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+----*--*-----+
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| ^
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Request | : Response
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v |
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/----------------------------------*--*-------------------------------------\
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| Public Network |
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\---*--*------------*--*-------------*--*------------*--*------------*--*---/
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^ ^ ^ ^ ^ ^ ^ ^ ^ ^
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| | | | | | | | | |
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| : | : | : | : | :
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v v v v v v v v v v
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+---*--*---+ +---*--*---+ +---*--*---+ +---*--*---+ +---*--*---+
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| Ceph MON | | Ceph MDS | | Ceph OSD | | Ceph OSD | | Ceph OSD |
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+----------+ +----------+ +---*--*---+ +---*--*---+ +---*--*---+
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^ ^ ^ ^ ^ ^
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The cluster network relieves | | | | | |
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OSD replication and heartbeat | : | : | :
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traffic from the public network. v v v v v v
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/------------------------------------*--*------------*--*------------*--*---\
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| cCCC Cluster Network |
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\---------------------------------------------------------------------------/
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There are several reasons to consider operating two separate networks:
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#. **Performance:** Ceph OSD Daemons handle data replication for the Ceph
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Clients. When Ceph OSD Daemons replicate data more than once, the network
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load between Ceph OSD Daemons easily dwarfs the network load between Ceph
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Clients and the Ceph Storage Cluster. This can introduce latency and
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create a performance problem. Recovery and rebalancing can
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also introduce significant latency on the public network. See
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`Scalability and High Availability`_ for additional details on how Ceph
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replicates data. See `Monitor / OSD Interaction`_ for details on heartbeat
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traffic.
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#. **Security**: While most people are generally civil, a very tiny segment of
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the population likes to engage in what's known as a Denial of Service (DoS)
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attack. When traffic between Ceph OSD Daemons gets disrupted, placement
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groups may no longer reflect an ``active + clean`` state, which may prevent
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users from reading and writing data. A great way to defeat this type of
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attack is to maintain a completely separate cluster network that doesn't
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connect directly to the internet. Also, consider using `Message Signatures`_
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to defeat spoofing attacks.
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IP Tables
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=========
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By default, daemons `bind`_ to ports within the ``6800:7300`` range. You may
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configure this range at your discretion. Before configuring your IP tables,
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check the default ``iptables`` configuration.
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sudo iptables -L
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Some Linux distributions include rules that reject all inbound requests
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except SSH from all network interfaces. For example::
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REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
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You will need to delete these rules on both your public and cluster networks
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initially, and replace them with appropriate rules when you are ready to
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harden the ports on your Ceph Nodes.
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Monitor IP Tables
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-----------------
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Ceph Monitors listen on port ``6789`` by default. Additionally, Ceph Monitors
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always operate on the public network. When you add the rule using the example
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below, make sure you replace ``{iface}`` with the public network interface
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(e.g., ``eth0``, ``eth1``, etc.), ``{ip-address}`` with the IP address of the
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public network and ``{netmask}`` with the netmask for the public network. ::
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sudo iptables -A INPUT -i {iface} -p tcp -s {ip-address}/{netmask} --dport 6789 -j ACCEPT
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MDS and Manager IP Tables
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-------------------------
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A :term:`Ceph Metadata Server` or :term:`Ceph Manager` listens on the first
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available port on the public network beginning at port 6800. Note that this
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behavior is not deterministic, so if you are running more than one OSD or MDS
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on the same host, or if you restart the daemons within a short window of time,
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the daemons will bind to higher ports. You should open the entire 6800-7300
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range by default. When you add the rule using the example below, make sure
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you replace ``{iface}`` with the public network interface (e.g., ``eth0``,
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``eth1``, etc.), ``{ip-address}`` with the IP address of the public network
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and ``{netmask}`` with the netmask of the public network.
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For example::
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sudo iptables -A INPUT -i {iface} -m multiport -p tcp -s {ip-address}/{netmask} --dports 6800:7300 -j ACCEPT
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OSD IP Tables
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-------------
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By default, Ceph OSD Daemons `bind`_ to the first available ports on a Ceph Node
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beginning at port 6800. Note that this behavior is not deterministic, so if you
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are running more than one OSD or MDS on the same host, or if you restart the
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daemons within a short window of time, the daemons will bind to higher ports.
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Each Ceph OSD Daemon on a Ceph Node may use up to four ports:
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#. One for talking to clients and monitors.
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#. One for sending data to other OSDs.
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#. Two for heartbeating on each interface.
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.. ditaa::
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/---------------\
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| OSD |
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| +---+----------------+-----------+
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| | Clients & Monitors | Heartbeat |
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| +---+----------------+-----------+
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| |
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| +---+----------------+-----------+
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| | Data Replication | Heartbeat |
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| +---+----------------+-----------+
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| cCCC |
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\---------------/
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When a daemon fails and restarts without letting go of the port, the restarted
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daemon will bind to a new port. You should open the entire 6800-7300 port range
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to handle this possibility.
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If you set up separate public and cluster networks, you must add rules for both
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the public network and the cluster network, because clients will connect using
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the public network and other Ceph OSD Daemons will connect using the cluster
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network. When you add the rule using the example below, make sure you replace
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``{iface}`` with the network interface (e.g., ``eth0``, ``eth1``, etc.),
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``{ip-address}`` with the IP address and ``{netmask}`` with the netmask of the
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public or cluster network. For example::
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sudo iptables -A INPUT -i {iface} -m multiport -p tcp -s {ip-address}/{netmask} --dports 6800:7300 -j ACCEPT
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.. tip:: If you run Ceph Metadata Servers on the same Ceph Node as the
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Ceph OSD Daemons, you can consolidate the public network configuration step.
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Ceph Networks
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=============
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To configure Ceph networks, you must add a network configuration to the
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``[global]`` section of the configuration file. Our 5-minute Quick Start
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provides a trivial `Ceph configuration file`_ that assumes one public network
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with client and server on the same network and subnet. Ceph functions just fine
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with a public network only. However, Ceph allows you to establish much more
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specific criteria, including multiple IP network and subnet masks for your
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public network. You can also establish a separate cluster network to handle OSD
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heartbeat, object replication and recovery traffic. Don't confuse the IP
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addresses you set in your configuration with the public-facing IP addresses
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network clients may use to access your service. Typical internal IP networks are
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often ``192.168.0.0`` or ``10.0.0.0``.
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.. tip:: If you specify more than one IP address and subnet mask for
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either the public or the cluster network, the subnets within the network
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must be capable of routing to each other. Additionally, make sure you
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include each IP address/subnet in your IP tables and open ports for them
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as necessary.
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.. note:: Ceph uses `CIDR`_ notation for subnets (e.g., ``10.0.0.0/24``).
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When you have configured your networks, you may restart your cluster or restart
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each daemon. Ceph daemons bind dynamically, so you do not have to restart the
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entire cluster at once if you change your network configuration.
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Public Network
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--------------
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To configure a public network, add the following option to the ``[global]``
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section of your Ceph configuration file.
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.. code-block:: ini
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[global]
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# ... elided configuration
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public network = {public-network/netmask}
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Cluster Network
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---------------
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If you declare a cluster network, OSDs will route heartbeat, object replication
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and recovery traffic over the cluster network. This may improve performance
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compared to using a single network. To configure a cluster network, add the
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following option to the ``[global]`` section of your Ceph configuration file.
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.. code-block:: ini
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[global]
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# ... elided configuration
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cluster network = {cluster-network/netmask}
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We prefer that the cluster network is **NOT** reachable from the public network
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or the Internet for added security.
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Ceph Daemons
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============
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Ceph has one network configuration requirement that applies to all daemons: the
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Ceph configuration file **MUST** specify the ``host`` for each daemon. Ceph also
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requires that a Ceph configuration file specify the monitor IP address and its
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port.
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.. important:: Some deployment tools (e.g., ``ceph-deploy``, Chef) may create a
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configuration file for you. **DO NOT** set these values if the deployment
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tool does it for you.
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.. tip:: The ``host`` setting is the short name of the host (i.e., not
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an fqdn). It is **NOT** an IP address either. Enter ``hostname -s`` on
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the command line to retrieve the name of the host.
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.. code-block:: ini
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[mon.a]
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host = {hostname}
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mon addr = {ip-address}:6789
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[osd.0]
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host = {hostname}
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You do not have to set the host IP address for a daemon. If you have a static IP
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configuration and both public and cluster networks running, the Ceph
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configuration file may specify the IP address of the host for each daemon. To
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set a static IP address for a daemon, the following option(s) should appear in
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the daemon instance sections of your ``ceph.conf`` file.
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.. code-block:: ini
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[osd.0]
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public addr = {host-public-ip-address}
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cluster addr = {host-cluster-ip-address}
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.. topic:: One NIC OSD in a Two Network Cluster
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Generally, we do not recommend deploying an OSD host with a single NIC in a
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cluster with two networks. However, you may accomplish this by forcing the
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OSD host to operate on the public network by adding a ``public addr`` entry
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to the ``[osd.n]`` section of the Ceph configuration file, where ``n``
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refers to the number of the OSD with one NIC. Additionally, the public
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network and cluster network must be able to route traffic to each other,
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which we don't recommend for security reasons.
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Network Config Settings
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=======================
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Network configuration settings are not required. Ceph assumes a public network
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with all hosts operating on it unless you specifically configure a cluster
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network.
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Public Network
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--------------
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The public network configuration allows you specifically define IP addresses
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and subnets for the public network. You may specifically assign static IP
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addresses or override ``public network`` settings using the ``public addr``
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setting for a specific daemon.
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``public network``
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:Description: The IP address and netmask of the public (front-side) network
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(e.g., ``192.168.0.0/24``). Set in ``[global]``. You may specify
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comma-delimited subnets.
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:Type: ``{ip-address}/{netmask} [, {ip-address}/{netmask}]``
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:Required: No
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:Default: N/A
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``public addr``
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:Description: The IP address for the public (front-side) network.
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Set for each daemon.
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:Type: IP Address
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:Required: No
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:Default: N/A
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Cluster Network
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---------------
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The cluster network configuration allows you to declare a cluster network, and
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specifically define IP addresses and subnets for the cluster network. You may
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specifically assign static IP addresses or override ``cluster network``
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settings using the ``cluster addr`` setting for specific OSD daemons.
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``cluster network``
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:Description: The IP address and netmask of the cluster (back-side) network
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(e.g., ``10.0.0.0/24``). Set in ``[global]``. You may specify
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comma-delimited subnets.
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:Type: ``{ip-address}/{netmask} [, {ip-address}/{netmask}]``
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:Required: No
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:Default: N/A
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``cluster addr``
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:Description: The IP address for the cluster (back-side) network.
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Set for each daemon.
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:Type: Address
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:Required: No
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:Default: N/A
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Bind
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----
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Bind settings set the default port ranges Ceph OSD and MDS daemons use. The
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default range is ``6800:7300``. Ensure that your `IP Tables`_ configuration
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allows you to use the configured port range.
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You may also enable Ceph daemons to bind to IPv6 addresses instead of IPv4
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addresses.
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``ms bind port min``
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:Description: The minimum port number to which an OSD or MDS daemon will bind.
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:Type: 32-bit Integer
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:Default: ``6800``
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:Required: No
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``ms bind port max``
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:Description: The maximum port number to which an OSD or MDS daemon will bind.
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:Type: 32-bit Integer
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:Default: ``7300``
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:Required: No.
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``ms bind ipv6``
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:Description: Enables Ceph daemons to bind to IPv6 addresses. Currently the
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messenger *either* uses IPv4 or IPv6, but it cannot do both.
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:Type: Boolean
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:Default: ``false``
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:Required: No
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``public bind addr``
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:Description: In some dynamic deployments the Ceph MON daemon might bind
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to an IP address locally that is different from the ``public addr``
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advertised to other peers in the network. The environment must ensure
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that routing rules are set correclty. If ``public bind addr`` is set
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the Ceph MON daemon will bind to it locally and use ``public addr``
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in the monmaps to advertise its address to peers. This behavior is limited
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to the MON daemon.
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:Type: IP Address
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:Required: No
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:Default: N/A
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Hosts
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-----
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Ceph expects at least one monitor declared in the Ceph configuration file, with
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a ``mon addr`` setting under each declared monitor. Ceph expects a ``host``
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setting under each declared monitor, metadata server and OSD in the Ceph
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configuration file. Optionally, a monitor can be assigned with a priority, and
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the clients will always connect to the monitor with lower value of priority if
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specified.
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``mon addr``
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:Description: A list of ``{hostname}:{port}`` entries that clients can use to
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connect to a Ceph monitor. If not set, Ceph searches ``[mon.*]``
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sections.
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:Type: String
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:Required: No
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:Default: N/A
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``mon priority``
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:Description: The priority of the declared monitor, the lower value the more
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prefered when a client selects a monitor when trying to connect
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to the cluster.
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:Type: Unsigned 16-bit Integer
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:Required: No
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:Default: 0
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``host``
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:Description: The hostname. Use this setting for specific daemon instances
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(e.g., ``[osd.0]``).
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:Type: String
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:Required: Yes, for daemon instances.
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:Default: ``localhost``
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.. tip:: Do not use ``localhost``. To get your host name, execute
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``hostname -s`` on your command line and use the name of your host
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(to the first period, not the fully-qualified domain name).
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.. important:: You should not specify any value for ``host`` when using a third
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party deployment system that retrieves the host name for you.
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TCP
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---
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Ceph disables TCP buffering by default.
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``ms tcp nodelay``
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:Description: Ceph enables ``ms tcp nodelay`` so that each request is sent
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immediately (no buffering). Disabling `Nagle's algorithm`_
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increases network traffic, which can introduce latency. If you
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experience large numbers of small packets, you may try
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disabling ``ms tcp nodelay``.
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:Type: Boolean
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:Required: No
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:Default: ``true``
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``ms tcp rcvbuf``
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:Description: The size of the socket buffer on the receiving end of a network
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connection. Disable by default.
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:Type: 32-bit Integer
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:Required: No
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:Default: ``0``
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``ms tcp read timeout``
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:Description: If a client or daemon makes a request to another Ceph daemon and
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does not drop an unused connection, the ``ms tcp read timeout``
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defines the connection as idle after the specified number
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of seconds.
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:Type: Unsigned 64-bit Integer
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:Required: No
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:Default: ``900`` 15 minutes.
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.. _Scalability and High Availability: ../../../architecture#scalability-and-high-availability
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.. _Hardware Recommendations - Networks: ../../../start/hardware-recommendations#networks
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.. _Ceph configuration file: ../../../start/quick-ceph-deploy/#create-a-cluster
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.. _hardware recommendations: ../../../start/hardware-recommendations
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.. _Monitor / OSD Interaction: ../mon-osd-interaction
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.. _Message Signatures: ../auth-config-ref#signatures
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.. _CIDR: https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing
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.. _Nagle's Algorithm: https://en.wikipedia.org/wiki/Nagle's_algorithm
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