Difference: DpmMigratingFromSL3TOSL4 (3 vs. 4)

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META TOPICPARENT name="DataManagementDocumentation"

How to migrate a DPM on SL3 to SL4

It is mandatory to read the whole page before performing any operations.
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You will have TO SCHEDULE A DOWNTIME. ALL THE SERVICES RELATED TO DPM WILL NEED TO BE STOPPED IN THE CORRECT ORDER, INCLUDING MYSQL SERVER.
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You will have TO SCHEDULE A DOWNTIME. ALL THE SERVICES RELATED TO DPM WILL NEED TO BE STOPPED IN THE CORRECT ORDER. You may also require to stop your MySQL server if the host needs to be reinstalled to SL4.
 

1. Introduction

The objective of this page is to give guidelines on safely migrating a DPM installed on SL3 to SL4. This document is meant for DPM site administrators. A DPM installation has 3 main components which can be installed or not on the same machine:
  • the DPM head node on which the daemons (dpm, dpns, srm*) run.
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  • service dpm-gsiftp stop

4.3 DPM MySQL

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In this section we describe how to move MySQL DB from SL3 to SL4 safely. This step needs to be performed if the MySQL server and the DPM headnode are located on the same machine or if you plan to reinstall your MySQL server which is located on a different machine from the DPM head node.
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In this section we describe how to move MySQL DB from SL3 to SL4 safely. This step needs to be performed if the MySQL server and the DPM headnode are located on the same machine or if you plan to reinstall your MySQL server which is located on a different machine from the DPM head node. If your MySQL server runs on another machine than the DPM head node, and you don't plan to reinstall the OS of the MySQL host, then you can skip this section.
 

4.3.1 A brief reminder

The DB is split into 2 parts :
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  • DPNS DB is the name server containing all information about the replicas and metadata. All paths to replicas of a file are stored in this DB.

4.3.2 DB backup

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N.B : if your MySQL server is used for other services than DPM, you will need to make a back up of the necessary databases. Please ask the support of the involved services. In this subsection, we focus only on the DPM service.
 
  • IT IS VERY IMPORTANT TO MAKE A BACKUP OF THE DPM AND DPNS DB BEFORE ANY REINSTALLATION.
  • For that the DPM server (headnode) must be stopped as for a DPM migration see LINK for more details on how to stop properly your DPM.
  • mysqldump --databases <dpm_db_name> <dpns_db_name> -u <username> -p > DPM_MySQL_BCKUP.sql will allow to make a backup of the dpm and dpns DBs
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 You may have to run it on the DPM head node and DPM disk servers separetely. See Yaim documentation for more details.
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6.2 Importing the data into MySQL

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6.2 Importing the data into MySQL (if your MySQL server is not affected by the reinstallation to SL4, you can skip this section)

 The MySQL server will be installed via Yaim. One remark, in SL4, the MySQL process is called mysqld and not mysql. If the version of the DPM you want to install is higher than the one you used to run in SL3, it is highly recommended to first load the data into the MySQL. It is important in case of an upgrade of the table schema. Yaim will then properly upgrade the table schema you had in SL3 if necessary. To perform this operation,
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7. Problems, questions, comments

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Q1. i don't have enough space to make a tar on the machine. What can Ido?
 
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A1: you can type the following command (from the DPM head node/disk server/ MySQL server) provided that you have an ssh client and a host where you can store the files:

tar czpf - <directory_to_tar> | ssh <login>@<host_where_to_put_the_tar> cat ">" <name_of_the_tar> 
It may prompt you for the password of the account. You can alos specify the location of your ssh key via ssh -i and the version of ssh to be used ssh -1 (default one) or ssh -2.

To get it back and untar it, you can type the following command (from the DPM head node/disk server/ MySQL server):

ssh <login>@<host_where_to_put_the_tar> cat "<" <name_of_the_tar> |tar xfz -
 Don't hesitate to report problems, to ask questions or make any comments to improve the quality of this page to DPM support
 
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