NetApp Insight: NetApp Data Motion Session

The presentation was given by Larry Touchette, Technical Marketing Engineer on the Virtualization Team.

Data Motion is a combination of NetApp technologies that will allow the non-disruptive migration of datasets from one storage system to another.  Think of it as storage vMotion for volumes.  The intent here is to move the data around the data center in a flexible way while maintaining uptime to the applications.  This is not designed to be a disaster recovery tool. 

How is this accomplished?  NetApp combines three key technologies together for this to happen: 1. MultiStore to provide vFiler capabilities, 2.semi-sync SnapMirror to transport the data from one site to another, and 3. Provisioning Manager as the management GUI.

Here is each technology briefly:

1. MultiStore allows the implementation of virtual storage systems, called vFilers.  Because the storage system is virtual, it is hardware independent and can be moved around.  Also, multiple storage systems can exist on the same physical unit.  The technology is similiar to virtual machines for NetApp systems.

2. Semi-sync SnapMirror allows the replication of the virtual storage system and the associated volumes from one location to another.  Because semi-sync is used, distance limitations will apply but they have not been determined at this time.  Flex vols are the only volume type supported.

3. Version 4.0 of Provisioning Manager will be released to enable this product.  This is will be a plug-in to Operations Manager 4.0 and will provide a GUI to allow the Data Motion functionality that will automate the migration process, including clean up.  You can also perform a roll back which will come in handy for temporary moves due to upgrades, planned downtime, etc.

The workflow will involve the copying of the data from one system to another (baseline transfer) as the first step.  After that, the datastores will stay up to date using semi-sync for replication.  When you are ready, you will perform a "cut over" from one site to the other.  For iSCSI and NFS, the migration will be considered similar to a cluster failover.  I/O will pause for a shortime but if the applications are configured correctly, the application will stay up.  Because CIFS is session based, CIFS sessions will drop and need to be reestablished.

Here is a list of the required products to make all of this happen:

• NFS/iSCSI/CIFS licenses
• Multistore
• Snap Mirror (Sync)
• Provisioning Manager 4.0

As with any other version 1.0 product, there are a number of design limitations:

• ONTAP 7.3.3 or 8.0.1 will be required
• Multistore vFilers do not support FC attached LUNs
• A common IP subnet is needed.  There is no ability to reassign IP information
• The source and destination must be on different arrays, you can not move within an array, including an HA pair
• You can only move from smaller NVRAM boxes to larger NVRAM boxes (this may mean one way transfers!)
• You can only move from slower drive speeds to faster drive speeds (this may mean one way transfers and no FC to SATA movement!)
• Traditional volumes are not supported
• Top level QTrees are not supported, QTrees are supported within a Flex vol
• All Flex vols owned by the vFiler are migrated
• Currently there are limits in place on the maximum number of Flex vols per vFiler.  I'm not going to publish them because they are likely to change before product release
• Snap Lock and Flex Cache are NOT supported
• deduped data will be moved but the dedupe fingerprint data will need to be regenerated on the destination after the migration
• FlexClones will be expanded at the destination (this is a SnapMirror behavior), the parent volume must be on the same vFiler
• File level FlexClones will remained deduped
• There is no way to do this from telnet, everything must be done using Provisioning Manager

In summary, the product looks nice and I think will be of value to large enterprises with multiple systems.  There are some pretty big limitations but they will be overcome in time.  What are your thoughts on the technology?