Data is a critical component in the operation and function of organizations. Hey, nothing new so far! Implementing data protection methodologies enables data centers to avoid disruptions in business operations. In every data center, there is a need to replicate data for disaster recovery and redundancy. To protect data from disasters, there is a need to implement replication technologies that enable you to securely store multiple copies of data. According to EMC, you still get the most flexible unified hybrid flash storage on the market with a VNX. And consolidate the most workloads at the lowest cost and best choice of replication that suits you. EMC announced several weeks ago, VDM MetroSync!
What is a VDM? A Data Mover is a component that runs its own operating system. It retrieves data from a storage device and makes it available to a network client. It's an EMC software feature that enables the grouping of Common Internet File Systems (CIFS) and/or Network File Systems (NFS) environments and servers into virtual containers. Each VDM has access only to the file systems mounted to that VDM, providing a logical isolation between physical Data Movers and other VDMs on the VNX system.
There are several ways to replicate on a VNX. The following replicaiton technologies are available
- VNX Replicator
- Replication Manager
The most discussed and used are MirrorView and VNX Replicator.
VNX MirrorView, and this has been around since the days of CLARiON can replicate over both FC and IP networks. MirrorView/S is distance limited and offers a disaster recovery solution with no data loss where the round trip delay is less than 10ms. (RTT is the length of time it takes for a signal to be sent plus the length of time it takes for an acknowledgment of that signal to be received.) 10ms is approximately equal to 200 kilometers. (there are dependancies) MirrorView/A provides replication over long distances. MirrorView/A can be used for replication between VNX systems which are separated by more than 10 ms RTT and up to 200 ms RTT. MirrorView/A is also optimized for low network bandwidth.
VNX Replicator is an asynchronous file system level replication technology for CIFS and NFS provides on the VNX. VNX Replicator is included in the Remote Protection Suite and the Total Protection Pack for VNX systems. But as mentioned it's asynchronous.
VDM MetroSync is a Disaster Recovery solution for VNX2 File which leverages a MirrorView/S replication session to create a zero data loss replication solution at a Virtual Data Mover.
It allows for replication of a VDM along with all of its contents including file systems, checkpoint schedules, CIFS servers, exports, interfaces, and so on. It can be configured in either an active/passive configuration where the active VDMs are constrained to one site, or an active/active configuration where each site has its own set of active VDMs. VDMs can be moved or failed over from one system to another as needed.
VDM MetroSync Manager is optional software that can be installed on a Windows server which works with VDM MetroSync. It provides a GUI interface to display VDM MetroSync session information and run operations to move, failover, or restore VDMs. It also has the ability to continuously monitor sessions and automatically initiate failover when issues are detected.
With synchronous replication enabled between two systems, it is also possible to add asynchronous replication to a third system by using Replicator. This allows the third system to be located further away and enables it to be used as a backup and recovery solution. When VDMs are moved or failed over between the VDM MetroSync systems, the Replicator sessions to the third system are preserved. Since the Replicator checkpoints are replicated along with the VDM, a common base checkpoint is available which removes the requirement for a full synchronization after failover. The Replicator sessions can be incrementally updated and restarted on the new system where the VDM is active.
Is EMC, slowly rising toward NetApp MetroCluster?