EMC PowerPath Migration Enabler (PPME) is a migration tool that enables non-disruptive or minimally disruptive data migration between storage systems or between logical units within a single storage system. Migration Enabler resides on the host and allows applications continued data throughout the migration process. Migration Enabler works independently of PowerPath multipathing. However, PowerPath must be
PowerPath Migration Enabler integrates with other technologies to minimize or
eliminate application downtime while migrating data.
I will show you how to perform the data migration using PPME. This demonstration environment includes one SQL 2008 server, two Brocade 300B SAN Switch, one source array CLARiiON CX4-120 and one target array VNX5200. One source volume (150GB) are mounted on this SQL server, the physical system diagram as below.
SQL Server – Microsoft Windows 2008 R2 SP1 + SQL Server 2008 R2 SP2 and installed EMC PowerPath 6.0 SP2
Source Array – EMC CLARiiON CX4-120c (FLARE 30)
Target Array – EMC VNX5200 (Block, VNX OE 32)
Brocade 300B (FOS 6.2) x 2
Now we start to setup the data migration, PowerPath Migration Enabler is a component of PowerPath, you can see it when you install EMC PowerPath. PowerPath and PowerPath Migration Enabler is required the license to enable.
NOTE: Make sure that EMC PowerPath Capabilities displays All.
The following is the migration procedure by using PowerPath Migration Enabler,
1. Firstly assign one target LUN (equal or larger capacity with source LUN) into SQL server.
2. Note the names of your source and target devices.
3. Setup the host copy session by PowerPath Migration Enabler.
4. Starts the host copy session.
5. After the host copy session is successfully completed, swap the source and target LUN.
6. Commit the LUN swapping.
7. Cleanup the host copy session.
8. Remove the source LUN in SQL server.
After assign the new LUN into SQL server, you need to online the disk in Disk Management. Disk 1 is source LUN and Disk 2 is target LUN.
Executes the PowerPath command “powermt display dev=all”, you can see Pseduo name in the output result. harddisk1 is the source LUN, harddisk2 is the target LUN.
Executes the PPME command to setup the host copy session, “powermig setup -src <source_pseudo> -tgt <target_pseudo> -techType hostcopy”
NOTE: 3 is Migration session ID.
Executes the PPME command to start the session, “powermig sync -handle <id>”. If you want to check migration state, you can check it by “powermig query -handle <id>” or “powermig info -handle <id>”. During the migration, the SQL service is still running.
Migration speed is controlled by the throttle value associated with the session. The throttle ranges from 0-9, 0 is the fastest mode and 9 is the slowest.
You can change the throttle value “powermig throttle -handle <id> -throttlevalue 1”
When the migration is successfully completed, you can see the state in sourceSelected.
Now you can swap the source and target LUN. To make sure the SQL service is non-disruptive, at the time time I start one SQL query in SQL server during the LUN swapping.
powermig selectTarget -handle <id>
After swap the source and target LUN, you can see the state in targetSelected. And the SQL service is still running and non-disruptive.
Next check whether performance is acceptable on target LUN. If it is no probem, you can commit the migration session: powermig commit -handle <id>
NOTE: You cannot fallback after commit the migration session.
Then cleanup the migration session, powermig cleanup -handle <id>
In this moment, you can execute powerpath command again “powermt display dev=all”, you can see the harddisk1 change to be target LUN, harddisk2 change to be source LUN.
Now Disk 1 is changed to be target LUN.
Finally you can remove the source LUN in SQL server, the data migration is completed.
If you have questions about PowerPath Migration Enabler Administration, you can look up the information material on support.emc.com.
If the target array is EMC Unity, PowerPath Migration Enabler is also supported on it.
The following documents can be found on EMC Online Support:
EMC Unity: Introduction to the EMC Unity Platform
EMC Unity: Replication Technologies
EMC Unity: Compression
Migrating to EMC Unity with SAN Copy: A “How-To” Guide
When migrating servers from one EMC storage system to another, there are basically two options: using storage features like SAN Copy, MirrorView/S or MirrorView/A. If your system only has limited service down time for data migration, PowerPath Migration Enabler is a good option, it is also supported on Microsoft Cluster service.