Archive for the ‘System Admin’ Category
Before the admin shutdown VIO server LPAR, admin must remember the following points:
- If client LPAR uses storage and networking virtual resources provided by VIO server then admin must deactivate the LPAR and then shutdown the client LPAR.
- Each shared memory partition must be a shutdown because every partition accesses its paging space device using VIO server LPAR that the admin is planning to shutdown.
To restart VIO server from HMC:
- Expand system management -> servers
- Click managed systems on which LPAR is located
- Select LPAR
- Click Operations -> Restart
- Click OK
And now complete the following task:
- Activate client LPAR
- Activate each shared memory partition that accesses paging space device using VIO server LPAR that is restarted.
P.S: Please refer the redhat IBM pdfs for detailed understanding!
# echo “Message” | mail –s “subject” –f firstname.lastname@example.org
This command is used to send mails.
# echo “Message” | mail –f <email@example.com> –s subject <firstname.lastname@example.org>
AIX File System And Logical Volume
1. All the file systems exist on top of logical volume. No file system can exist without logical volume. Although LV does exists without a file system. First a LV is created and on top of it a FS is created. System first creates a LV. Then, a layer of jfs is created on top of it. Once the jfs is created then FS is finally created.
2. Whenever a file system is expanded, logical volume (LV) is extended first. Then the layer of jfs on top of it is expanded and finally the file system is expanded.
3. AIX has a limit of only 3 copies of LV. These copies may be in sequential or parallel arrangements.
4. In case system crash takes place, Mirror write consistency check (MWCC) method is performed in order to track the last 62 writes to the mirrored LV.
5. In normal VG configuration, a VG can never have more than 32 PVs as VGDA design has a limit and is always fixed in size. VG will not take any extra disk once the quota of 32 PVs is full.
6. LVCB contains the following information:
- LV creation date
- Mirrored LV information
- Mount points in JFS file system
7. LVCB consists of first 512 bytes of LV.
8. LV Theoretical limits:
i. Number of PVs = 32
ii. PP’s per PV = 1016
iii. PP size = 1 MB to 1 GB
iv. Number of LV = 256
v. LV size (maximum) = 32 x 1016 x 128 = 8.3 TB (approx.)
9. Reorgvg command takes lot of I/O capacity so it is always recommended to run this command when workload is low.
Most of the information is already available in various Red Hat IBM pdfs and online books.
Hope you enjoyed reading this post.
This post will discuss about the system boot with respect to Hardware.
- Bosboot Command:
As we have already seen, bosboot command is used to create boot image from disk files and copies boot image to BLV.
This question is asked many a times in interviews.
- If the boot device is:
- Removable Media: if the boot device is removable media like tape or cd, it boots to install and maintenance menu.
- Network adapter: it will depend on NIM configuration for client machine.
- Disk: depends upon the service key whether:
If a machine keeps rebooting and repeating POST, it means either there is invalid bootlist or corrupted BLV or hardware failure of boot device.
- To fix corrupted BLV:
- Insert CD
- Press F5 to go in SMS Mode
- Once in the Maintenance Mode, access the RVG
- Run the following command
# bosboot –ad /dev/hdisk0
# shutdown –Fr
Disable Root Login:
Method to disable root login:
Add rlogin = false in /etc/security/user and root name in /etc/nologin and ‘PermitRootLogin No’ in /etc/ssh/sshd_config
Edit HMC Password:
For P4 and P5 machines,
Command used is:
# hscroot@hmc > chhmcusr –u hscroot –t passwd
Enter new password:
Retype new password:
To reboot HMC from command line:
Login to HMC using SSH, login as hscroot user and run the following command:
# hscroot@hmc > hmcshutdown –t now -r
To Check HMC Version:
# lshmc -V
To know address of HMC which manage LPAR:
# lsrsrc IBM.ManagementServer
Hope this post was informative.
1. Command used for listing of /dev directory:
# ls –l /dev
2. Predefined means supported. (PdDv)
# lsdev –PH
3. Customized means configured / defined (entry in ODM class CuDV) / available (CuDV)
Command used is:
# lsdev –CH
4. How is the location code understood:
AB-CD together is adapter
HACMP is integrated with AIX 5L OS and system P servers.
HACMP Version 5 supports Linux OS.
HACMP supports the following applications:
HACMP also supports CUoD, CBU, CoD, Lpar.
CUoD stands for capacity upgrade on demand.
CUoD means activation of processors or memory.
CBU stands for capacity backup upgrade.
CBU basically means processors or memory temporarily added to backup server.
CoD stands for on/off capacity on demand.
CoD means ability to activate the processors or memory resources temporarily.
HACMP Version 5.4 supports non IBM Harwares as well and Operating Systems like Red Hat Linux and SUSE.
RMC stands for Resource Monitoring and Control.
Note, AIX 5L V5.3 supports Mozilla on 32 bit OS.
To start documentation from command line, Command used is:
P.S: Information published in this post is inspired from various red hat pdf’s and online sources.