diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/rados/configuration/mon-lookup-dns.rst | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/doc/rados/configuration/mon-lookup-dns.rst b/doc/rados/configuration/mon-lookup-dns.rst new file mode 100644 index 00000000..e32b3206 --- /dev/null +++ b/doc/rados/configuration/mon-lookup-dns.rst @@ -0,0 +1,51 @@ +=============================== +Looking op Monitors through DNS +=============================== + +Since version 11.0.0 RADOS supports looking up Monitors through DNS. + +This way daemons and clients do not require a *mon host* configuration directive in their ceph.conf configuration file. + +Using DNS SRV TCP records clients are able to look up the monitors. + +This allows for less configuration on clients and monitors. Using a DNS update clients and daemons can be made aware of changes in the monitor topology. + +By default clients and daemons will look for the TCP service called *ceph-mon* which is configured by the *mon_dns_srv_name* configuration directive. + + +``mon dns srv name`` + +:Description: the service name used querying the DNS for the monitor hosts/addresses +:Type: String +:Default: ``ceph-mon`` + +Example +------- +When the DNS search domain is set to *example.com* a DNS zone file might contain the following elements. + +First, create records for the Monitors, either IPv4 (A) or IPv6 (AAAA). + +:: + + mon1.example.com. AAAA 2001:db8::100 + mon2.example.com. AAAA 2001:db8::200 + mon3.example.com. AAAA 2001:db8::300 + +:: + + mon1.example.com. A 192.168.0.1 + mon2.example.com. A 192.168.0.2 + mon3.example.com. A 192.168.0.3 + + +With those records now existing we can create the SRV TCP records with the name *ceph-mon* pointing to the three Monitors. + +:: + + _ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon1.example.com. + _ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon2.example.com. + _ceph-mon._tcp.example.com. 60 IN SRV 10 60 6789 mon3.example.com. + +In this case the Monitors are running on port *6789*, and their priority and weight are all *10* and *60* respectively. + +The current implementation in clients and daemons will *only* respect the priority set in SRV records, and they will only connect to the monitors with lowest-numbered priority. The targets with the same priority will be selected at random. |