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DR Series Best Practice Guide
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Video Conferencing, limits can be applied to the DR traffic to allow that application the required
bandwidth.
Keep in mind, when setting bandwidth throttling policies on a container replicating between two
physical DR appliances, the policy will be applied for all containers between the replicated devices. For
example, containers 1 and 2 on a DR appliance are set to replicate to a secondary DR appliance. When
bandwidth throttling is set on container 1, the bandwidth on the second container will also be
throttled.
Replication schedules can be set to ensure one container gets more time replicating (for high priority
data) or to schedule replication to occur in off-peak hours, although in most situations it is
recommended to leave the default settings and let replication transfer data as needed over the
network.
When multiple containers are being replicated between the same DR appliances, the replication
engine round-robins the requests across the containers. In this situation the containers may not be
replicated in synchronicity if there are large amounts of data waiting to be transferred.
Replication Encryption
For best performance vs. security, encryption settings should be set at 128 bit encryption, providing a
good balance for most environments. For situations where the replicated data is being transferred
across the open Internet, it is strongly recommended to tunnel the replication traffic through an
encrypted VPN tunnel.
Addressing Packet Loss
Occasionally a given link between two sites may introduce packet loss, resulting in slow data transfer
or replication processes that terminate due to errors or a simple timeout. When packet loss arises due
to slow links, higher speed links, jitter or high latency, the window size may need to be adjusted to
account for this. In such instances please contact the Dell Support department, and they will assist in
custom tuning the window size for the particular link.
Replication Tuning
In some instances it may be beneficial to prevent replication from running all the time. Consider the
following scenarios when deciding whether to replicate on a per-container basis.
High Bandwidth Conditions
In situations where bandwidth is very high between a source and destination DR appliance, or many
sources are replicating to a single target appliance, the backup window may be negatively impacted
when backups occur during the replication process. If the backup window is unacceptable in such a
scenario, the replication should be rescheduled to occur outside the backup window, or the available
bandwidth should be limited to < 50MB/s.
A high bandwidth scenario is when the WAN Bandwidth or Bandwidth between the source and
destination DR units is > 100MB/s (800Mbits).