Businesses have recognized that information is an asset that must be managed and utilized as would any critical resource. At the forefront of IT management's responsibilities is ensuring uninterrupted access to information. Loss of data or inability to access data directly translates into lost opportunity and revenue.

Data replication via mirroring is the only way to provide uninterrupted real-time data availability. The presence of a mirror or duplicate set of live production data online guarantees data availability in case of a primary system failure.

Procom Technology offers ProMirror, an asynchronous near real-time mirroring architecture. Available as a software option on all Procom filers, ProMirror ensures that a block-equivalent mirror of any NetFORCE file volume can be maintained almost any distance from the source.

ProMirror SAM Architecture
ProMirror uses the Safe Asynchronous Mirroring (SAM) architecture to create a copy of a volume on a remote filer. Here we shall take a closer look at the various aspects of the ProMirror architecture.

Source/Target Interconnection
ProMirror implementation consists of a target and source file volume, along with the interconnecting network. Using a standard network as the interconnecting medium, ProMirror offers the flexibility of both local and remote data replication. All communications between the data source and target utilize the TCP/IP protocol.

Block-level Mirroring
With ProMirror, data replication is performed at the block level. This architecture is similar to RAID 1 disk mirroring except that the connecting medium between mirror devices is a network. All checkpoints, symbolic links, and other data structures existing on the target will be identical to those the source volume. ProMirror's block-level implementation transmits only those data blocks that have changed.

Safe Asynchronous Mirroring (SAM)
ProMirror is architected with Safe Asynchronous Mirroring technology. Both ends of the mirror have a dedicated mirror logs that log changes to both source and target file systems. Updates to a target filer are comprised of a series of write transactions, each containing a number of data block updates. Each transaction is sent from source to target in an ordered fashion and entered into the target mirror log. Each of these write transactions contain a number of key file system updates such as inode delete and update.

ProMirror Applications
ProMirror can be used to help address many data management challenges facing IT professionals today:

Disaster Recovery
ProMirror eliminates the need for lengthy tape restores and enhances recovery time in case of a complete loss of data. With ProMirror properly configured, the target, or mirror, is assured to be an accurate, near real-time representation of the offline source filer. The NetFORCE target file volume can be brought online quickly to ensure uninterrupted operations.

Backup

A ProMirror target volume may be dedicated for backing up source volumes. ProMirror enhances operations by moving backup I/O to the remote volume.

This shadowprocessing capability reduces CPU load on the production filer, streamlining operations.

Data Distribution
For businesses with remote locations, ProMirror simplifies data distribution. NetFORCE filers running ProMirror can be used to push data from a central location, such as a corporate headquarters, to a satellite office without relying on FTP or other passive file transfer methods.

Data Migration
ProMirror can be configured to enhance data availability with planned migrations. Once a mirror is established between a source and target filer, any data updates will be reflected at the new location. When the data migration is ready to be integrated, the target volume is promoted to a live volume. This enables the source volume to remain online up until the integration can be commenced.