HP DL360 Serial Attached SCSI storage technology, 2nd Edition - Page 16

Figure 14. The zone manager can be attached to an end device (top) or directly to one or more expanders through a sideband interface (bottom). The zone manager assigns zone groups to all zoning expander phys, and it assigns all phys in a wide port to the same zone group. The zone manager stores the zoning assignment of each expander phy along with SAS addresses in the zoning expander's route table. Inside a particular ZPSDS, the zone manager assigns each zoning expander phy attached to another zoning expander phy to zone group 1. Basically, phys in zone group 1 have access to phys in all zone groups. The zone manager assigns each zoning expander phy on the boundary of the ZPSDS to a zone group other than group 1. The ZPSDS boundary is defined by designating expander phys as ―not trusted‖ when connected to end devices outside the zone. Each zoning expander device also contains a zone permission table that controls whether a connection is allowed between phys in different zone groups. SAS performance Enterprise-class SAS hard disk drives (HDDs) must provide maximum performance 24x7 and under continuous I/O workload in high-vibration environments. An important factor in HDD performance is seek time, which is the time from when a read or write action is initiated until the data transfer from or to the disk actually begins. The smaller platters of SFF SAS drives inherently yield lower seek times, which is an advantage in file servers with frequent random accesses. 16