Chapter 3. Knowing Your Storage Options
The type of storage you choose to run your virtual infrastructure on makes a big difference in how well your system will work. You have several choices for protocols and drive technology, and all of them have their advantages and disadvantages. You need to decide what is the correct fit for your situation. This chapter describes the various options available. Before discussing any options, you need to understand SCSI anatomy.
SCSI Anatomy 101
To fully understand your storage options and make informed decisions, you need to understand SCSI. The rest of this chapter has some technical details, but they shouldn't be too painful.
Like the Open Systems Interconnection (OSI) networking model, SCSI makes use of several layers offering different functionality. The official name for this model is the SCSI Architecture Model (SAM), and a simplified version is shown in Figure 3-1. This three layer model consists of commands, transport protocols, and interconnects:
SCSI commands: The commands are actual directives to send or retrieve data from a SCSI device. Commands can be shared and common to all SCSI devices, or they can be specific to a particular type of SCSI device like a hard drive.
SCSI transport protocols: These protocols are responsible for grouping data into chunks for transmission, monitoring the transmission for success, and picking what data blocks go to which device. Some protocols you'll likely be interested in are iSCSI and Fibre Channel, ...
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