Amount of RAM
4GB
8GB
12GB
3.4. Stream Size Guidance
This section provides guidelines you can use to size storage volumes for large stream sizes. The
largest object a DX Storage cluster can store is one-fifth the size of the largest volume in the cluster.
If you attempt to store a larger object, DX Storage logs an error and does not store the object.
To further tune your hardware planning, keep in mind that the DX Storage health processor reserves
defragmentation space on a volume equal to twice the size of the largest stream that has been
stored on a volume. Therefore, you might end up having much lower storage capacity than you
expect.
If possible, size your hardware so that the largest streams consume between 10 and 20 percent
of available space on disk drives used in the storage cluster. If the largest stream consumes 10 to
20 percent of disk drive space, you get 60% utilization of available space. The percent utilization
improves as you add more disk space.
For example, if the largest stream consumes between 5 and 10% of disk space, utilization improves
to 80%. If the largest stream consumes only 1.25 to 2.5% of available disk space, utilization is 95%.
If disk utilization is diminishing, you should consider upgrading the size of the disk drives in your
cluster nodes.
3.5. Adaptive Power Conservation
As of the 4.0 release, DX Storage includes an adaptive power conservation feature that
supplements DX Storage's naturally green characteristics to spin down disks and reduce CPU
utilization after a configurable period of inactivity. A cluster that is constantly in use will likely not
benefit significantly from the adaptive power feature but a cluster that has long periods of inactivity
on nights and weekends can expect significant power savings utilizing this feature. Because only
inactive nodes are affected, max available throughput will not be affected, though additional latency
will be incurred on the first access to a sleeping node. The cluster will automatically awake one
or more nodes to carry out requests when needed and eventually revive all nodes if needed. The
configuration parameters that control the adaptive power conservation features can all be set in the
node and/or cluster configuration files.
If a node has not serviced any incoming SCSP requests (both client and internode) in the last
configurable sleepAfter seconds, it will change to an idle status and pause its health processor,
allowing the associated disks to eventually turn idle as well after they have had no IO activity
in the past sleepAfter seconds. When an application or another node in the cluster once again
begins sending SCSP requests, one or more of the nodes in the cluster will awake to service those
requests. Even if no outside activity is detected for a long period, each node will awake after it has
been idle for the configurable wakeAfter seconds so that the health processor can monitor disk and
content integrity.
In addition to the sleepAfter and wakeAfter parameters, a new archiveMode setting allows an
administrator to designate a new or empty node as an archive node that will remain idle in low-
power mode without participating in cluster activity until its capacity is needed. This allows
administrators to have additional capacity online and available without paying for the associated
Copyright © 2010 Caringo, Inc.
All rights reserved
Maximum number of immutable
unnamed streams
33 million
66 million
132 million
16
Maximum number of unnamed
anchor streams or named
streams
16 million
33 million
66 million
Version 5.0
December 2010
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