Adding MDS Servers

The procedure of setting up the first MDS server is described in Setting Up the First Metadata Server . To configure a second and all subsequent MDS servers for a cluster, follow the steps below:

1. Make sure that you remember the exact name of the Parallels Cloud Storage cluster where you want to add an MDS server. The example below uses pcs1 as the cluster name.
2. Log in to the computer you want to configure as an MDS server and add to the cluster as root or as a user with root privileges.
3. Download and install the following RPM packages on the computer: pstorage-ctl , pstorage-libs-shared , and pstorage-metadata-server .

   These packages can be installed with this command:

   # yum install pstorage-metadata-server

4. Make sure that cluster discovery is configured for the server. For details, see Configuring Cluster Discovery .
5. Authenticate the server in the cluster.

   This step is required only if the physical server where you are setting up the MDS server has never been authenticated in the cluster before. For example, you can skip this step if you have already configured the server as a chunk server or a client. Otherwise, run the following command to authenticate the server in the cluster:

   # pstorage -c pcs1 auth-node

   Please enter password for cluster:

   During its execution, the command asks you for the password to validate the server. Enter the password you specified when setting up the first MDS server and press Enter. pstorage then compares the provided password with the one stored on the MDS server, and if the passwords match, successfully authenticates the server.

6. Create the MDS server and add it to the cluster:

   # pstorage -c pcs1 make-mds -a 10.30.100.102 -r /pstorage/pcs1-mds

   In the command above:

   • pcs1 is the name of the cluster you are adding the MDS server to.
   • 10.30.100.102 is the IP address of the new MDS server.

     Replace 10.30.100.102 in the example above with the IP address of your own MDS server. The specified IP address must be (1) static (or in the case of using DHCP, mapped to the MAC address of the MDS server) and (2) chosen from the range of IP addresses on the BackNet network dedicated to your Parallels Cloud Storage cluster. See Network Requirements for details.

   • /pstorage/pcs1-mds is the path to a journal that will store the information about the pcs1 cluster. When choosing a directory for storing the journal, make sure that the partition where the directory is located has at least 10 GB of free disk space.

   If the DNS records or Zeroconf discovery is not configured in your network, you need to additionally use the -b option and specify the IP addresses of the first MDS server (and all other MDS servers, if you have more than one in your cluster) when running the command:

   # pstorage -c pcs1 make-mds -a 10.30.100.102:2510 -r /pstorage/pcs1-mds -b 10.30.100.101

7. Start the MDS management service ( pstorage-mdsd ) and configure it to start automatically on the MDS server boot:

   # service pstorage-mdsd start

   # chkconfig pstorage-mdsd on

For instructions on how to check that the MDS server has been successfully configured for your cluster, see Monitoring Parallels Cloud Storage Clusters .