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
Data replication via mirroring is the only way to provide
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
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.
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 can be used to help address many data management
challenges facing IT professionals today:
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.
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.
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.
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.