Expanded storage cannot be defined for a CF image. Only IBM CFCC can run in CF mode. 

GLYPH<SM590000> Linux only mode 

In Linux only mode, storage addressing can be 31 bit or 64 bit, depending on the operating system architecture and the operating system configuration. 

Only Linux and z/VM operating systems can run in Linux only mode. Linux on Z 64-bit distributions (SUSE Linux Enterprise Server 10 and later, Red Hat RHEL 5 and later, and Ubuntu 16.04 LTS and later) use 64-bit addressing and operate in z/Architecture mode. z/VM also uses 64-bit addressing and operates in z/Architecture mode. 

GLYPH<SM590000> z/VM mode 

In z/VM mode, certain types of processor units can be defined within one LPAR. This feature increases flexibility and simplifies systems management by allowing z/VM to run the following tasks in the same z/VM LPAR: 

– Manage guests to operate Linux on Z on IFLs 

– Operate z/VSE and z/OS on CPs 

– Offload z/OS system software processor usage, such as Db2 workloads on zIIPs 

– Provide an economical Java execution environment under z/OS on zIIPs 

GLYPH<SM590000> Secure Service Container (SSC) mode 

In SSC mode, storage addressing is 64 bit for an embedded product. This configuration allows for an addressing range up to 16 EB. However, the current z14 ZR1 definition limit for LPARs is 8 TB of storage (physical memory limit). 

Currently, the z/VSE Network Appliance (available on z14 ZR1) runs in an SSC LPAR. 

## 3.7.3 Reserved storage 

Reserved storage can be optionally defined to an LPAR, which allows a nondisruptive image memory upgrade for this partition. Reserved storage can be defined to central and expanded storage, and to any image mode except CF mode. 

An LPAR must define an amount of main storage and optionally (if not a CF image), an amount of expanded storage. Main storage and expanded storage can have the following storage sizes defined: 

GLYPH<SM590000> The initial value  is the storage size that is allocated to the partition when it is activated. 

GLYPH<SM590000> The reserved value  is another storage capacity beyond its initial storage size that an LPAR can acquire dynamically. The reserved storage sizes that are defined to an LPAR do not need be available when the partition is activated. They are predefined storage sizes to allow a storage increase, from an LPAR point of view. 

Without the reserved storage definition, an LPAR storage upgrade is a disruptive process that requires the following steps: 

1. Partition deactivation. 

2. An initial storage size definition change. 

3. Partition activation. 

The extra storage capacity for an LPAR upgrade can come from the following sources: 

GLYPH<SM590000> Any unused available storage 

GLYPH<SM590000> Another partition that features released storage 

GLYPH<SM590000> A memory upgrade 

