NIM (Network Installation Manager) is a IBM AIX Service used for remote unattended installation similar to the Sun/Oracle Jumpstart and RedHat Kickstart or PXE without DVD/CD used to install AIX in many servers at a time in an Infra. Now, the installation of VIO and Linux can also be performed using NIM. Apart from installation, upgradation and maintainig AIX softwares/filesets the management activities like backup and restore of mksysb can be performed via NIM. By using NIM Master to store mksysb can reduce usage of tape device and time duration.
Activities performed by NIM
1) New Installation (Pull method)
2) TL/SP upgradation
3) OS Migration/Upgradation
4) mksysb backup/restore
5) Provide boot CD image for maintenance activities
6) Centralized repository for Filesets
7) Used to restore missed files in the mksysb backup
Components of NIM
The following are the important components involved in NIM installation, confiugration and managment.
1. Master (NIM Master)
As named NIM Master server is the repository of all the softwares, OS images, mksysb backup which serves the same to its clients for the corresponding operations.
2. Client (NIM Client)
Systems which are managed by NIM Master server for the operations like installation, backup and restoration
3. Resources (NIM Resources)
This can be a single file or up to a whole filesystem that is used to provide some sort of information to, or perform an operation on a NIM client. Resources are allocated to NIM clients using NFS and can be allocated to multiple clients at the same time. The NIM resources are lpp_source,SPOT,mksysb,bosinst_data and image_data
4. Resource Server
Server where resources are available. NIM client can also act as Resource Server. But in most cases NIM Master server will be the resource server. Briefly discuss types of resources in consecutive sections.
5. NIMSH Daemon (NIM Service Handler)
For environments where the standard "rsh" protocol are not enough secure, at the time "nimsh". Using the port nos 3901 and 3902
6. Allocate/Allocation :
This process is what allows your NIM client to access resources in NIM. The master uses NFS to perform the allocation process. Resources can be allocated to one or more NIM clients at the same time
It is just a directory which acts as source of installation which contains the following
* OS image cd/dvd
* TL/SP updates
These type of resources can be used for all NIM clients.
b) SPOT (Shared Processor Object Tree)
It is similar to boot cd, we can boot the nimclient using the SPOT. It contains the "/usr" part i.e., kernel, filesets, device drivers and BOS install programs.
There are 2 types of SPOT i) lppspot and ii) mksysbspot and these types of SPOT are specific to particular NIM client or can be used for all NIM clients.
In general, rootvg backup is the mksysb backup which may be specific to particular NIM client.
Important advantages are quick restoration of crashed OS and can create customized (hardened) mksysb backup of particular which could be installed/resotred in other servers to avoid fresh installation and performing hardening.
Customized Installation Procedure (bosinst.data) which is used in non-interactive installation, mainly POST installation changes.
image.data (rootvg architecture) layout of LV,VG,PP information and its architecture.
a) bootp protocol (BOOTPD)
This is the initial communication made between NIM master and client during network boot.
b) Trivial File Transfer Protocol (TFTPD)
It is used to transfer lppsource,SPOT and other resources from NIM server to NIM client during the NIM client booting.
Check the services are running,#lssrc -ls inetd
bootps /usr/sbin/bootpd bootpd /etc/bootptab active
tftp /usr/sbin/tftpd tftpd -n active
#grep bootps /etc/services
bootps 67/tcp # Bootstrap Protocol Server
bootps 67/udp # Bootstrap Protocol Server
#grep tftp /etc/services
tftp 69/udp # Trivial File Transfer
tftp 69/tcp # Trivial File Transfer
If the above services are not enabled, start the same.
#chubserver -v bootp -p udp -a
#chubserver -v tftpd -p udp -a
#refresh -s inetd
Also, ensure NFS group related services are also enabled.#startsrc -g nfs
Important Directories and Files
When we create SPOT, kernel is copied into /tftpboot directory . All kernles of NIM clients are in the direcotryroot@aixnim1: /etc # ls -l /tftpboot
lrwxrwxrwx 1 root system 34 Dec 19 18:36 aix21.domain.com -> /tftpboot/spot_5200-08.chrp.mp.ent
-rw-r--r-- 1 root system 1276 Dec 19 18:36 aix21.domain.com.info
-rw-r--r-- 1 root system 9379964 Dec 8 15:31 spot_5200-08.chrp.64.ent
-rw-r--r-- 1 root system 9260943 Dec 8 15:31 spot_5200-08.chrp.mp.ent
File which authenticate nim client for remote boot up for nim operations like bos installation, restoration & maintenance boot. Based on the NIM operation, nim client info update and once the NIM operation completed, entry also removed automatically from this file.
In simple words, authenticates NIM client for remote boot up.
The fields are separated with colon (:) and attributes are separated with equal sign (=):
first field - NIM client name
bf - boot file name
ip - NIM client IP address
ht - hardware type
sa - TFTP server address for the boot file
gw - gateway used by client to reach the server
sm - subnet mask for the nim client
The file always exists on the NIM master and client. contains information about who is master and client, port no, protocol informations.
This is automatically generated when master was created and client was registered to master. This file was not manually edited. If any corrupted, want to be removed and recreated.
1)Rebuild on Master
2)Rebuild on Client
#nimint -a master=<MASTER_HOSTNAME> -a name=<CLIENT_NIM_NAME>
Useful NIM Basics Link