EMC Storage Product Knowledge Sharing

PowerPath Migrator Enabler is a host-base migration tools from EMC that allows you to migrate data between storage systems with little or no interruption to data access. This tool can be use in conjunction with other underlying technology such as EMC Invista, Open Replicator. PPME use the PowerPath filter dirvers to provide non-disruptive or minimally disruptive migrations. Only specific host plateforms are supported by PPME. Please check EMC support matrix for supported host systems. One of the PPME features that supports pseduo-to-pseduo, native-to-native and native-to-pseudo device migration.

Consider the following when designing and configuring PPME:

Ø Remote devices do not have to be the same RAID type or meta-configuration.
Ø Target devices must be the same size or large than the source control device.
Ø Target directors act as initiators in the SAN.
Ø Contrary to the recommendations for Open Replicator, the source device remains online during the “hot pull.”
Ø The two storage systems involved in the migration must be connected directly or through a switch, and they must be able to communicate.
Ø Every port on the target array that allows access to the target device must also have access to the source device through at least one port on the source array. This can be counter to some established zoning policies.
Ø Since PPME with Open Replicator uses FA resources, determine whether this utility will be used in a production environment. In addition, consider FA bandwidth assessments so that appropriate throttling parameters (that is, pace or ceiling).
Ø The powermig throttle parameter sets the pace of an individual migration by using the pace parameter of Open Replicator:
Ø Faster (lower throttle) makes the migration faster, but may impact application I/O performance.
Ø Slower (higher throttle) makes the migration slower.
Ø The default is five (midpoint).
Ø When setting a ceiling to limit for Open Replicator throughput for a director/port:
Ø The ceiling value is set as a percentage of a director/port’s total capacity.
Ø The ceiling can be set for a given director, port, director and port, or all director and ports in the Symmetrix array.
Ø To set ceiling values, you must use symrcopy set ceiling directly (powermig does not provide a way to do this)
Ø Once the hot pull has completed, remove or re-use the source device.
Ø Do not forget to “clean up” the zoning once you have completed migration activities.
Hope this will be useful in migration planning or selecting migration tools. I will try to explain in deatil in coming post such as PPME with Open Replicator, Solution Enabler etc..

Auto-provisioning requires Enginuity 5874 or later. It simplify Symmetrix provisioning by allowing you to create group of devices like storage group in CLARiiON, Front-End Port Group and Host Initiators Group and then associate these groups with each other in a masking view.

The following are the basic steps for provisioning Symmetrix using Auto-Provisioning:-

1) Create a Storage Group
2) Create a Port Group
3) Create an Initiator Group
4) Associate the groups in a Masking View.

Creating Storage Group:- It is component of Auto-Provisioning group and FAST ( Will discuss about FAST in later post), both require Enginiuity 5874. The maximum number of storage group allowed per array is 8192. A storage group can contain up to 4096 devices. A Symmetrix device can belong to more than one storage group.

Note:- By default Dynamic LUN addresses will assigned to each device. If can manually assign the host LUN addresses for the device you are adding to the group by clicking Set LUN Address- Storage group dialog box.

Creating Port Group:- A port can belong to more than one port group and port must have the ACLX bit enabled. For example if you want FA 5A and 12 A for windows operating system, you can create port group name called WIN_PortGrp or Win_FA5A_FA12A_PrtGrp etc.

Creating Initiator Group:- The maximum number of initiator groups allowed per Symmetrix array is 8000. An initiator group can contain up to 32 initiator of any type and contain other initiator groups (cascaded to only one level).

Initiator Group name must be unique from other initiator groups on the array and cannot exceed 64 characters. Initiator group names are case-insensitive.

Creating Masking view:- It just a co-relation between Storage Group, Port Group and Initiator Group and you are done! Device will be mapped automatically to selected port group and masked to selected initiator groups.

Symmetrix Optimizer improves array performance by continuously monitoring access patterns and migrating devices to achieve balance across the disks in the array. This is process is carried out automatically based on user-defined parameters and is completely transparent to end users, hosts and applications in the environment. Migration is performed with constant data availability and consistent protection.

Optimizer performs self-tuning of Symmetrix data configurations from the Symmetrix service processor by:
· Analyzing statistics about Symmetrix logical device activity.
· Determining which logical devices should have their physical locations swapped to enhance Symmetrix performance.
· Swapping logical devices and their data using internal Dynamic Reallocation Volumes (DRVs) to hold customer data while reconfiguring the system (on a device-to-device basis).

Symmetrix Optimizer can be utilized via EMC Symmetrix Management Console or SYMCLI, where user can defines the following:

1) Symmetrix device to be optimized
2) Priority of those devices.
3) Window of time that profiles the business workload.
4) Window of time in which Optimizer is allowed to swap.
5) Additional business rules.
6) The pace of the Symmetrix Optimizer volume copy mechanism.

After being initialized with the user-defined parameters, Symmetrix Optimizer operates totally autonomously on the Symmetrix service processor to perform the following steps.

1) Symmetrix Optimizer builds a database of device activity statistics on the Symmetrix back end.

2) Using the data collected, configuration information and user-defined parameters, the Optimizer algorithm identifies busy and idle devices and their locations on the physical drives. The algorithm tries to minimize average disk service time by balancing I/O activity across physical disk by locating busy devices close to each other on the same disk, and by locating busy devices on faster areas of the disks. This is done by taking into account the speed of the disk, the disk geometry and the actuator speed.

3) Once a solution for load balancing has been developed the next phase to carry out the Symmetrix device swaps. This is don using established EMC Timefinder technology, which maintains data protection and availability. Users can specify if swaps should occur in completely automated fashion or if the user is required to approve Symmetrix device swaps before the action is taken.

4) Once the swap function is complete, Symmetrix Optimizer continues data analysis for the next swap.

How Symmetrix Optimizer works:-

1) Automatically collects logical device activity data, based upon the devices and time window you define.

2) Identifies “hot” and “cold” logical devices, and determines on which physical drives they reside.

3) Compares physical drive performance characteristics, such as spindle speed, head actuator speed, and drive geometry.

4) Determines which logical device swaps would reduce physical drive contention and minimize average disk service times.

5) Using the Optimizer Swap Wizard, swaps logical devices to balance activity across the back end of the Symmetrix array.

Optimizer is designed to run automatically in the background, analyzing performance in the performance time windows you specify and performing swaps in the swap time windows you specify.