User guide

52 | Working with the AppAssure 5 Core
Performance Considerations for Replicated Data Transfer
If the bandwidth between the source core and the target core cannot accommodate
the transfer of stored recovery points, replication begins with seeding the target core
with base images and recovery points from the selected servers protected on the
source core. The seeding process only has to be performed once, as it serves as the
foundation that is required for regularly scheduled replication.
When preparing for replication, you should consider the following factors:
 Change Rate. The change rate is the rate at which the amount of protected data
is accumulated. The rate depends on the amount of data that changes on
protected volumes and the protection interval of the volumes. If a set of blocks
change on the volume, reducing the protection interval reduces the change rate.
 Bandwidth. The bandwidth is the available transfer speed between the source
core and the target core. It is crucial that the bandwidth be greater than the
change rate for replication to keep up with the recovery points created by the
snapshots. Due to the amount of data transmitted from core to core, multiple
parallel streams may be required to perform at wire speeds up to the speed of a
1GB Ethernet connection.
NOTE: Bandwidth specified by the ISP is the total available bandwidth. The outgoing
bandwidth is shared by all devices on the network. Make sure that there is enough
free bandwidth for replication to accommodate the change rate.
 Number of Agents. It is important to consider the number of agents protected
per source core and how many you plan to replicate to the target. AppAssure 5
lets you perform replication on a per-protected server basis, so you can choose
to replicate certain servers. If all protected servers must be replicated, this
drastically affects the change rate, particularly if the bandwidth between the
source and target cores is insufficient for the amount and size of the recovery
points being replicated.
Depending on your network configuration, replication can be a time-consuming
process.
The Maximum Change Rate for WAN Connection Types is shown in the table below
with examples of the necessary bandwidth per gigabyte for a reasonable change
rate.
Broadband Bandwidth Max Change Rate
DSL 768 Kbps and up 330 MB per hour
Cable 1 Mbps and up 429 MB per hour
T1 1.5 Mbps and up 644 MB per hour
Fiber 20 Mbps and up 8.38 GB per hour
For optimum results, you should adhere to the recommendations listed in the table above.