Compaq StorageWorks HSG60 ACS Solution Software V8.6 for Compaq Tru64 UNIX Installation and Configuration Guide

Planning Storage 2–5
Figure 2–3. PTL addressing in a dual-bus configuration
When the controller receives an I/O request, it identifies the storageset unit number for
the request, then correlates the unit number to the storageset name. From the storageset
name, the controller locates the appropriate device(s) for the I/O request (For example,
the RAIDset “RAID1” might contain DISK10000, DISK20000 and DISK10100). The
controller generates the read or write request to the appropriate device(s) using the
PTL addressing convention. Figure 2–4 illustrates the concept of mapping unit numbers to
PTL addresses.
Figure 2–4. Mapping a unit to physical disk drives
Model 4254 Disk Enclosure Shelf 1 (dual-bus)
Bus A Bus B
Bay 1 2 3 4 5 6 7 8 9 10 11 12 13 14
SCSI ID 00 01 02 03 04 05 08 00 01 02 03 04 05 08
DISK ID
Disk10000 Disk10100 Disk10200 Disk10300 Disk10400 Disk10500 Disk10800 Disk20000 Disk20100 Disk20200 Disk20300 Disk20400 Disk20500 Disk20800
D100
RAID1
Disk 10000 Disk 20000 Disk 30000
Storageset
name
Host addressable
unit number
Controller
PTL addresses
CXO6186B