power costs of the additional nodes. For more information about sleepAfter, wakeAfter,
and archiveMode settings, see the node configuration appendix in the DX Object Storage
Administration Guide.
3.6. Proactive Power Conservation
In addition to the power savings gained from the adaptive power conservation feature,
administrators may need the ability to proactively reduce the power consumption peak and flatten
the power spectrum consumption of the grid where power caps are required for either budgetary
or compliance reasons. To support this use case, DX Storage allows administrators to optionally
set the power cap for the cluster to a percentage of the maximum potential power consumption via
either the admin console Settings pop-up or SNMP. It is highly likely that the power cap mode will
result in some performance degradation so administrators should be aware of the potential impact to
throughput prior to setting the power cap to anything lower than 100%. Note this feature is currently
supported only on select Dell hardware.
Note
If the power cap percentage is changed using SNMP or the Admin Console and the
corresponding cluster settings UUID is not updated in DX Storage configuration, the
admin console and SNMP may get out of sync with the actual node state, as the power
cap is preserved across reboots even if the cluster settings UUID is not persisted.
3.7. Local Area Replication Using Subclusters
Local area replication (LAR) allows you to create logical separations in a DX Storage cluster to
define storage distribution strategies. These logical separations change the normal behavior of
the cluster so that DX Storage attempts to create the greatest logical spread between a stream's
replicas by moving them into separate subclusters. If your cluster boots from a CSN, contact your
support representative for instructions on manually configuring subclusters because the CSN
Console does not currently support this.
Examples where LAR subclusters are useful:
• Splitting a cluster based on location (data cabinet, building wing)
• Grouping nodes based on common infrastructure (network, power)
An example of splitting a cluster based on location is a company that has data centers in separate
wings of their building and wishes to have copies of stored content exist in both wings in case of a
partial building loss. A loss could be events like a fire, flooding, or air conditioning problems.
Similar to location based separation, you might wish to split a cluster based on common
infrastructure. Examples are grouping nodes by shared network switches, a common Power
Distribution Unit (PDU), or a common electrical circuit with in a rack.
The network connections between LAR subclusters must have the same speed and latency
characteristics as the connections between the nodes. Additionally, all nodes must be in the same
broadcast domain such that they are able to send data directly to all other nodes in the cluster and
receive the multicast traffic sent from anywhere in the cluster.
Warning
Avoid frequent changes to the subcluster assignments for nodes. When nodes move
to new subclusters, there is the potential for a lot of cluster activity while content is
redistributed to account for the new subcluster assignments.
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Version 5.0
December 2010
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