Chapter 6 HPSS ConfigurationHPSS Installation Guide September 2002 309Release 4.5, Revision 2VV Block Size The size of the logical datablock on the new virtualvolume.A 32-bit integer value. First multipleof MediaBlock Sizewhich equalsor exceeds1MB.Advice: The VV Block Size chosen will determine the performance characteristics ofthe virtual volume. This value must meet the following constraining requirements:(1) it must be an integer multiple of the Media Block Size. (2) For tape, it must bean even divisor of the virtual volume section size (Media Block Size * Blocks BetweenTape Marks). For example, if the Media Block Size is 64 KB, and the Blocks BetweenTape Marks is 512, the virtual volume section size is 32 MB. The VV Block Sizecould be 64 K, 128 K, 256 K, or larger, but not 192 K. See Sections 2.9.1.2 and2.9.1.3 for more details on selecting a good value for VV Block Size.PV Estimated Size The estimated amount ofdata that can be written onthe tape physical volume.Any positive 64-bit integer value. Based onselectedMedia TypeAdvice: See Section 2.9.1.10 for considerations on selecting a good value for PVEstimated Size.PV Size The size of a disk PV inthe storage class, in bytes.Any positive non-zero 64-bit value.Must be a multiple of the VV BlockSize and the Media Block Size.See section2.9.1.10 forconsiderationson selectingdisk PV Sizevalues.Stripe Width The number of physicalvolumes in a virtualvolume.For tape: 1 - 16For disk: 1 - 2561.Stripe Length The number of bytes in astripe.This value is calculated by SSM. Itis the product of the specified VVBlock Size and Stripe Width fields.Same as VVBlock Size.Device I/O Rate The approximate datatransfer speed, in kilobytesper second, which can beachieved by devicescorresponding to “MediaType”. For Tape, this fieldis used in calculating areasonable setting for“Blocks Between TapeMarks” (see below). ForDisk, this field is mostlyinformational.Any positive 32-bit integer valueThe value should, however, be asclose as possible to the actual I/Ospeed of the device.Based onselectedMedia Type.Table 6-11 Storage Class Configuration Variables (Continued)Display Field Name Description Acceptable Values DefaultValue
