Dell DX6004S DX Object Storage Getting Started Guide - Page 19

Amount of RAM 4GB 8GB 12GB Maximum number of immutable unnamed streams 33 million 66 million 132 million Maximum number of unnamed anchor streams or named streams 16 million 33 million 66 million 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 lowpower 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 16 Version 5.0 December 2010