IBM 990 ESA/390 mode

6947ch02.fm Draft Document for Review April 7, 2004 6:15 pm
68 IBM eServer zSeries 990 Technical Guide
Figure 2-18 Modes and memory diagram
Table2-9 shows the z990 storage allocation and usage possibilities, which depend upon the
image and architecture modes.
Table 2-9 Storage definition and usage possibilities
Remember that either a z/Architecture mode or an ESA/390 architecture mode operating
system can run in an ESA/390 image mode on a z990. Any ESA/390 image can be defined
with more than 2 GB of central storage and can have expanded storage. These options allow
you to configure more storage resources than the operating system is capable of addressing.
ESA/390 mode
In ESA/390 mode, storage addressing can be 31 or 64 bits, depending on the operating
system architecture and the operating system configuration.
An ESA/390 mode image is always initiated in 31-bit addressing mode. During its
initialization, a z/Architecture operating system can change it to 64-bit addressing mode and
operate in the z/Architecture mode.
Image mode Architecture mode
(addressability) Maximum central storage Expanded storage
Architecture z990
definition z990 definable Operating system usage
ESA/390 z/Architecture (64-bit) 16 EB 128 GB yes only by z/VM
ESA/390 (31-bit) 2 GB 128 GB yes yes
ESA/390 TPF ESA/390 (31-bit) 2 GB 128 GB yes yes
Coupling Facility CFCC (64-bit) 16 EB 128 GB no no
Linux Only z/Architecture (64-bit) 16 EB 128 GB yes only by z/VM
ESA/390 (31-bit) 2 GB 128 GB yes yes
z990
Mode
Logically
Partitioned
Mode
ESA/390 Mode
ESA/390 TPF Mode
Coupling Facility Mode
Linux Only Mode
CPs
CPs only
ICFs and/or CPs
IFLs or CPs
Image
Modes
CS < = 128 GB
ES = Yes
CS < = 128 GB
ES = Yes
CS < = 128 GB
ES = No
CS < = 128 GB
ES = Yes
CPs and zAAPs
Definable Central Storage (CS)
and Expanded Storage