What you will learn from this tip: This tip looks at automated data movement in a tiered storage environment to support information lifecycle management (ILM); performance and capacity load balancing; compliance; and technology upgrades or replacements. Learn what you need to be aware of when implementing automated data migration technology.
Data movement refers to moving or migrating data from a source to a destination. For the purposes of this discussion, this excludes backup, replication or mirroring. You can learn more about automating for business continuance and disaster recovery in my August 2006 Storage magazine article "Automate Disaster Recovery."
Data movement and migration are used interchangeably to generically describe data relocation in entirety or partially. It is important to understand the context in which data movement and migration is being used. For example, you could make a complete copy of a file from one location to another and delete the original. Another example is when a partial copy is made, in which some of the data is copied to a new location, and the file header, or a stub file, is left on the original Fibre Channel (FC) disk location.
Questions and items to be aware of regarding automatic data movement include:
- What is the scope of the policy manager, what storage systems, servers and other software will it work with to integrate into your environment?
- How are policies defined; are there templates or wizards to help set up polices?
- What additional technologies (hardware, software, appliances) and services are required to implement transparent and automated data movement?
- Can a policy manager issue or receive triggers and alerts from other policy managers to take action or request that actions to be performed?
- Is data movement transparent to the user and application, or does an application or server need to discover a new mount point, logical unit number (LUN) or volume after migration?
- Do applications pause while data is moved or migrated, or when data is copied back to a primary location when accessed? Or, is data transparently accessible without delay from wherever it has been moved to?
Some vendors' technologies utilize rule-based automated policy management and movement of data combined with transparent access of moved and migrated data. Other vendors feature automated data movement based upon rules. However, there can be delays while waiting for data to be copied back to the source location when accessed or delays incurred while data is being moved. Some vendors provide transparent data access and movement with no application disruption, however, some intervention is needed to invoke the data movement process.
What this all means is that you need to ask questions of technology providers to understand what their technologies can and cannot do to meet your needs and avoid surprises. Some questions to ask include:
- Is data movement (source to target) automated, how, when and via what rules?
- Is data movement 100% transparent to applications while being moved?
- Is migrated and moved data 100% transparent when accessed or is there a delay?
- How does the solution scale, what is the performance impact and concerns?
- Where does the policy manager reside, and what technologies can it work with?
- Can the technology perform cleanup operations, including deleting moved files?
Technologies incorporating some level of automated data movement or migration with different degrees of transparency are offered by primary storage vendors along with network attached storage (NAS) and virtual tape library (VTL) vendors among others. Some solutions migrate and move data within a box or storage system, while others can move data between like storage systems and others across heterogeneous technologies. Some technology will be storage system based, while others are network or appliance based with some being host server based.
The list of vendors supporting some type of automated data movement continues to grow and includes BlueArc Corp., EMC Corp., IBM, Innovation Data Processing, Incipient Inc., LeftHand Networks Inc., Softek Storage Solutions Corp., StoreAge Networking Technologies and many others. To avoid surprises with automated data movement, ask questions and do your due diligence to understand the capabilities of various technologies, including how transparent the data movement and access to your applications will be.
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