Dell PowerVault 220S Manual

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A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02PAGE 4 11/17/2005Understanding each of the storage components with respect to these attributes will help inmaking intelligent decisions to determine an optimal configuration for a given application.The paper presumes that the reader has a basic understanding of different levels of RAIDand interconnects technologies – Parallel SCSI (SPI-4), PCI vs. PCI-X vs. PCI-e. Thispaper presents a study of all storage components, as identified earlier, against variousstorage applications and different operating environments; however, specific behavior ofeach of the storage applications and management functions is beyond the scope of thisdocument. In this document we present storage solution from Parallel SCSI perspective,specifically for Dell’s Direct Attached Storage (DAS) products. Other storage technologiessuch as SAS, SATA, or Fibre Channel, as well as topologies such as Network AttachedStorage (NAS) or Storage Area Network (SAN) are outside the scope of this document. Allstorage applications referred to herein are treated independent of any specific host systemor server.2. Storage Applications and ComponentsIdentify customer usage model and needsIn order to select the correct storage solution for any given situation, it is important tounderstand what the application and user requirements will be for that solution. A goodstarting point is to have an understanding of basic storage profiling considerations.• Table 2-1: Storage Profiling ConsiderationsCharacteristic Values DescriptionPerformance• Bandwidth (MB persec.)• I/O size (KB/MB)• I/O Profile (read/writeand random/sequentialaccess mix)• LatencyPerformance is the overall ability of the solution to readand write data to disk. The performance requirementsare usually determined by the type of application beingutilized. Different applications have differentperformance requirements. For example, a databaseor e-mail server has mostly random disk accessoperations while a streaming media server would havemostly sequential disk access.Storage CapacityNeeds GigabytesStorage capacity is the current amount of storagespace required by the application and user data. Forexample, e-mail storage for 100 users would requiremuch less storage capacity than an e-mail store for1000 users.Storage GrowthRatePercent increase peryearStorage growth is the expected increase in the amountof capacity that will be required as usage of the serverincreases. This is usually measured in the expectednumber of users or clients accessing the serverCriticality Low, Medium, High,Very HighCriticality defines the impact to mission critical businessneeds if the storage is offline. This characteristic isimportant for choosing the right RAID level, anddetermining if clustering is needed.Picking a solution based on the application profileOne of the most important factors to consider when selecting a storage solution is the typeof application that will be utilizing the storage solution. This defines the overall purpose of