Listing the available memory blocks

Red Hat Enterprise Linux 9.2 LPAR mode z/VM guest

List the available memory to find out how much memory is available and which memory blocks are online.

Procedure

Use the lsmem command to list your memory blocks.

Example:

# lsmem -a
Address range                          Size (MB)  State    Removable  Device
===============================================================================
0x0000000000000000-0x000000000fffffff        256  online   no         0
0x0000000010000000-0x000000001fffffff        256  online   no         1
0x0000000020000000-0x000000002fffffff        256  online   no         2
0x0000000030000000-0x000000003fffffff        256  online   yes        3
0x0000000040000000-0x000000004fffffff        256  online   yes        4
0x0000000050000000-0x000000005fffffff        256  offline  -          5
0x0000000060000000-0x000000006fffffff        256  offline  -          6
0x0000000070000000-0x000000007fffffff        256  offline  -          7

Memory device size  : 256 MB
Memory block size   : 256 MB
Total online memory : 1280 MB
Total offline memory: 786 MB

Alternatively, you can list the available memory blocks by listing the contents of /sys/devices/system/memory. Read the state attributes of each memory block to find out whether it is online or offline.
Example: The following command results in an overview for all available memory blocks.
```
# grep -r --include="state" "line" /sys/devices/system/memory/
/sys/devices/system/memory/memory0/state:online
/sys/devices/system/memory/memory1/state:online
/sys/devices/system/memory/memory2/state:online
/sys/devices/system/memory/memory3/state:online
/sys/devices/system/memory/memory4/state:online
/sys/devices/system/memory/memory5/state:offline
/sys/devices/system/memory/memory6/state:offline
/sys/devices/system/memory/memory7/state:offline
```
Note: Online blocks are in use by your Linux® instance. An offline block can be free to be added to your Linux instance but it might also be in use by another Linux instance.