Preparing for Data Migration
This chapter describes how to prepare for a data migration job. It includes the following sections:
Planning a Data Migration Job
Traditional data migration is a complex procedure, which requires coordination of activities that may be performed by vendor representatives and multiple IT groups. Activities may need to occur at specific times to minimize service disruption.
Cisco MDS DMM is designed to minimize the dependency on multiple organizations, and is designed to minimize service disruption. However, even with Cisco MDS DMM, data migration is a complex activity. We recommend that you create a plan to ensure a smooth data migration.
To create your data migration plan, follow these steps:
Step 1 Document the SAN topology for the data migration. Identify and obtain any additional equipment and software licenses.
Step 2 Design the mapping of source LUNs to destination LUNs.
a. Identify the LUNs that need to be migrated and the impacted servers. The Server Lunmap Discovery (SLD) tool provides assistance in identifying this information. (See “Checking the Storage ASL Status” section for additional information about the SLD tool).
b. Calculate the storage requirements of the new LUNs. Identify the LUNs on the new storage subsystem. The new storage LUNs need to be the same size or larger than the matching existing storage LUN.
Step 3 Develop a schedule for the migration job.
a. Identify any required equipment and resources. Availability of external resources (such as a vendor service representative) may impact your schedule.
b. Identify periods of low user activity and I/O activity to minimize disruption during the migration. Cisco MDS DMM provides features to minimize user impact. For example, you can schedule the migration to run during non-peak hours or configure a slow migration rate.
c. Identify any required pre-migration configuration changes. (These changes are described in the following sections.)
d. Plan for one short window in which service is not be available during server reconfiguration. (This enables you to access the new storage after the data migration is completed).
Step 4 As a precaution, ensure that all the critical data on the existing storage have a recent back up.
Prior to performing a data migration job, ensure that the existing storage, the new storage, and the fabric switches are configured as required.
Note Starting from NX-OS 4.1(1b), Server Lunmap Discovery Module is a part of DMM provisioning. DMM must be enabled using the ssm enable feature module command before running the SLD tool.
The following sections describe the tasks to be completed:
Configuring MSM-18/4 Modules or MDS 9222i Switches
The Cisco MDS DMM feature executes on the MSM-18/4 module or MDS 9222i switch. The DMM feature supports data migration for storage LUNs exposed anywhere on the SAN fabric (that is, the storage port can be connected to the switch hosting the MSM-18/4 module or MDS 9222i switch or to another switch).
If necessary, provision an MSM-18/4 module or MDS 9222i switch in each fabric. We recommend that you install the MSM-18/4 module or the MDS 9222i switch on the switches that are connected to the existing storage ports.
If the existing or new storage port is on a different module or switch than the MSM-18/4 module and MDS 9222i switch, ISL network traffic will increase during the migration. This is because all traffic between the existing and new storage is directed through the MSM-18/4 module or MDS 9222i switch. Also, if the server port is on a different module or switch than the MSM-18/4 module or MDS 9222i switch, ISL network traffic will increase during the migration, as all traffic between the server and the storage is directed through the MSM-18/4 module or MDS 9222i switch.
Ensure that Cisco MDS DMM is the only active intelligent application on the MSM-18/4 module or MDS 9222i switch being used for the data migration job.
Configuring the Existing and New Storage
Complete the following configuration tasks for the storage devices:
- New Storage—Connect the new storage to the SAN. Create LUN maps and LUN masks. Configure access lists for the new storage.
- Existing Storage—Check that the LUNs are mapped.
- VSANs—Ensure that the existing storage and new storage port pair in each fabric is configured in the same VSAN. Also ensure that for each existing storage port VSAN, there is at least one new storage port and the server port has to be configured in the same VSAN.
- Zones—Optionally, you can reconfigure zoning to add new storage. Cisco MDS DMM does not enforce zoning for the new storage. If you do not configure the zoning before migration, you must complete this action before server accesses the new storage.
Checking the Storage ASL Status
The DMM feature contains the Array-Specific Library (ASL), which is a database of information about specific storage array products. DMM uses the ASL to correlate the LUN maps between multipath port pairs.
Use the Server LUN Discovery (SLD) tool to check the ASL status of LUNs on a storage array port. If the LUNs are all ASL=Yes, the Cisco MDS DMM feature automatically correlates the LUN maps.
If some or all of the LUNs result in ASL=No, contact Cisco support.
The SLD tool is launched from the supervisor module CLI. To check the status of a storage port, follow these steps:
switch# sld module module number vsan vsan no server-pwwn server pWWN target-pwwn target pWWN discover
Runs the SLD tool to discover the LUNs associated with the specified source and destination port pair.
switch# show sld module module number vsan vsan no server-pwwn server pWWN target-pwwn target pWWN [ detail ]
Displays the ASL status for LUNs associated with the specified source and destination port pair. The detail option displays the detailed output for the source and destination port pair.
The following example shows how to display ASL status for a storage port:
switch# show sld module 4 vsan 100 server-pwwn 21:00:00:e0:8b:08:5e:3e target-pwwn 50:06:0e:80:04:2c:5c:70
Id LUN Id Device Type Size Vendor Product Id Serial Number ASL Status
1 0x0 DASD 1.95GB VendorA ModelB5 11356 Yes Active
2 0x1 DASD 1.95GB VendorA ModelB5 11356 Yes Active
3 0x2 DASD 1.95GB VendorA ModelB5 11356 Yes Active
4 0x3 DASD 1.95GB VendorA ModelB5 11356 Yes Active
Figure 4-1 Server LUN Discovery Tool (SAN, Host, and Storage Port)
Before creating a migration job, you need to ensure that the server and storage ports are included in enclosures.
If the server ports are not already included in existing enclosures, you need to create enclosures for the server ports. If the server has multiple single-port HBAs, all of these ports need to be included in one enclosure. Enclosures for existing and new storage ports are created automatically.
Configuring the SAN Fabric
If the SAN is a heterogeneous SAN, you may need to install new MDS switches or adjust the SAN topology to meet DMM requirements. For additional information about SAN topologies, refer to Chapter3, “Understanding DMM SAN Topologies”