Power 775 Diskless Considerations - IBM Power Systems 775 Manual

2.1 Power 775 diskless considerations

The service node is the only LPAR in the Power 775 frames that is diskfull. The utility,
compute, and storage nodes are diskless.
that is not booted off disk. The following node states are available:
Diskfull node
For AIX systems, this node has local disk storage that is used for the operating system (a
stand-alone node). Diskfull AIX nodes often are installed by using the
install
Diskless node
The operating system is not stored on local disk. For AIX systems, the file systems are
mounted from a NIM server. An AIX diskless image is essentially a SPOT, which provides
a /usr file system for diskless nodes and a root directory. The contents of the file system
are used for the initial diskless nodes root directory. This node also provides network boot
support.
You choose to have your diskless nodes as
node, you must use a NIM root resource. If you want a stateless node, you must use a NIM
shared_root resource.
Stateful node
A stateful node maintains its state after it is shut down and rebooted. The node state is
any node-specific information that is configured on the node. For AIX diskless nodes, each
node has its own NIM root resource that is used to store node-specific information. Each
node mounts its own root directory and preserves its state in individual mounted root file
systems. When the node is shut down and rebooted, any information that is written to a
root file system is available.
Stateless node
A stateless node that does not maintain its state after it is shut down and rebooted. For
AIX diskless nodes, all of the nodes use the same NIM shared_root resource. Each node
mounts the same root directory. Anything that is written to the local root directory is
redirected to memory and is lost when the node is shut down. Node-specific information
must be re-established when the node is booted.
The advantage of stateless nodes is that there is less network traffic and fewer resources
are used, which is important in a large cluster environment.
2.1.1 Stateless system versus Statelite system
A stateless system is one type of diskless system that does not save data during a reboot.
Any data that is written to writable directories is lost. Differences also exist in how AIX and
Linux implement stateless. The common recommendation for both platforms on the Power
775 system is to implement statelite. A statelite stateless diskless system offers the option to
make some data read/write or persistent.
An AIX stateless system mounts the operating system over NFS. This is a common image
that is used by all nodes so that the /usr file system cannot be modified. A Linux stateless
system loads the entire image into memory (ramdisk) so the user writes to any location.
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IBM Power Systems 775 for AIX and Linux HPC Solution
methods.
Diskless
is a generic term that describes a system
stateful stateless
or . If you want a stateful
NIM rte mksysb
or