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authorQiaowei Ren <qiaowei.ren@intel.com>2018-01-04 13:43:33 +0800
committerQiaowei Ren <qiaowei.ren@intel.com>2018-01-05 11:59:39 +0800
commit812ff6ca9fcd3e629e49d4328905f33eee8ca3f5 (patch)
tree04ece7b4da00d9d2f98093774594f4057ae561d4 /src/ceph/doc/rados/configuration/mon-lookup-dns.rst
parent15280273faafb77777eab341909a3f495cf248d9 (diff)
initial code repo
This patch creates initial code repo. For ceph, luminous stable release will be used for base code, and next changes and optimization for ceph will be added to it. For opensds, currently any changes can be upstreamed into original opensds repo (https://github.com/opensds/opensds), and so stor4nfv will directly clone opensds code to deploy stor4nfv environment. And the scripts for deployment based on ceph and opensds will be put into 'ci' directory. Change-Id: I46a32218884c75dda2936337604ff03c554648e4 Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
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+===============================
+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.