Planning a NAS migration project

NAS migration: We want to migrate our existing file share to a NetApp filer. What is the best way to do it?

In a NAS migration project, as with any data migration project, planning is key to success.

All migrations follow the same basic methodology, with the following stages: discovery/planning, provisioning, pre-migration tasks, migration, validation.

Here I will focus on the migration phase and will describe two NAS migration scenarios.

There are many ways to migrate data, each with its own pros and cons. Often it will include use of migration utilities that can run on the host, storage or network layer; and data can be moved in two basic ways, by copying or by mirroring.

The migration methodology can vary based on factors such as:

• Source and destination storage systems
• Physical locations
• Specific applications and data dependencies
• Customer business, technical and operational requirements

In the NAS migration examples below the first approach is a manual migration effort while the second approach uses global namespace functionality. Global namespace provides a method of viewing and accessing files independent of physical location and gives administrators the ability to add, change and move files without affecting how users view and access those files.

Manual migration

When performing a manual migration, there are couple of tools--free and commercial--that can help. Examples of free tools are:

• Robocopy and Xcopy (Microsoft)
• Rsync and cpio scripts (Unix/Linux)

Although these tools help automate a migration, when you move data from one storage device to another, some manual steps still need to be performed, such as when creating shares, notifying users of new paths to shared folders and modifying application links.

The main risks associated with such migrations are lengthy planning periods required, regulatory requirements checks, difficulties of backing out of the migration, and sometimes budget overruns due to unpredicted workloads incurred.

Having said that, a manual approach is common for one-time NAS migration tasks.

Global namespace migration

Using global namespace allows you to migrate nondisruptively with data copied in the background to the new storage device. Once the copy is complete, you can redirect users to the new share without reconfiguring client mappings.

There are many tools that can help with global namespace migrations, such as those from F5, AutoVirt Software (NFS is on its roadmap for late 2011) and Microsoft as well as Unix/Linux tools such as Andrew File System (AFS).

The main challenges associated with migrations using global namespace are the same as for manual migration methods.

Conclusion

There is more than one right way to perform data migration, and deciding which one to go for is all about the business, technical and operational needs of your organisation. The entire planning phase should focus on developing the most effective migration plan for the specific circumstances. During the planning phase, make sure to work with key stakeholders so you understand the business and operational requirements of the migration and its likely impacts. By the time it comes to actually migrating data, all the upfront planning and analysis should have been done, and the migration plan will serve as the implementation guide.