Configuration: Disk Groups and Virtual Disks 113NOTE: If you selected the Custom option, select your preferred dynamiccache read prefetch setting (enabled/disabled) and segment size (8KB to512KB).2 Click OK.Choosing an Appropriate Physical Disk TypeYou can create disk groups and virtual disks in the storage array. You mustselect the capacity that you want to allocate for the virtual disk from eitherunconfigured capacity or free capacity available in the storage array. Then youdefine basic and optional advanced parameters for the virtual disk.With the advent of different physical disk technologies, it is now possible tomix physical disks with different media types and different interface typeswithin a single storage array. In this release of MDSM, the following mediatypes are supported:• Hard physical disk• Solid State Disk (SSD)Physical Disk Security with Self Encrypting DiskSelf encrypting disk (SED) technology prevents unauthorized access to thedata on a physical disk that is physically removed from the storage array. Thestorage array has a security key. Self encrypting disks provide access to dataonly through an array that has the correct security key.The self encrypting disk or a security capable physical disk encrypts dataduring writes and decrypts data during reads. For more information, see thePowerVault Modular Disk Storage Manager online help topics.You can create a secure disk group from security capable physical disks. Whenyou create a secure disk group from security capable physical disks, thephysical disks in that disk group become security enabled. When a securitycapable physical disk has been security enabled, the physical disk requires thecorrect security key from a RAID controller module to read or write the data.All of the physical disks and RAID controller modules in a storage array sharethe same security key. The shared security key provides read and write accessto the physical disks, while the physical disk encryption key on each physicaldisk is used to encrypt the data. A security capable physical disk works like anyother physical disk until it is security enabled.
