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Command to check RAM in AIX UNIX The bootinfo command uses the device configuration databases in information searches. Just type the following command as the root user: bootinfo -r It will displays amount of real memory in kilobytes. bootinfo command may not be available in latest AIX UNIX version, try following command: $ lsattr -El sys0 | grep realmem svmon command - Captures and analyzes a snapshot of virtual memory The svmon command displays information about the current state of memory. The displayed information does not constitute a true snapshot of memory, because the svmon command runs at user level with interrupts enabled. To print out global statistics, type: # svmon -G Read the man page of svmon for more information.

To reduce the size of a logical volume, use the lvreduce command. If the logical volume contains a file system, be sure to umount it and reduce the file system first. Umount the file system # umount   /file_system_name Check if all data structures of you logical volume are cleaned. # fsck -f /dev/vgname/lvname   Resize the file system # resize -p /dev/vgname/lvname 500M Reduce the logical volume  # lvreduce -L 500M /dev/vgname/lvname  Checking   df -h /file_system_name

To increase the size of a Logical Volume, use the   lvextend command. After extending the Logical volume, you will need to increase the size of associated file system , # lvextend -L 1500M /dev/vgname/lvname After it is necessary to increase the file system size to match. # resize2fs -p /dev/vgname/lvname -p option show the progress of the operation.

To add SCSI disks to your RHEL6 system without rebooting your machine, you have to rescan the newly disks using the following commands. If you are running your OS  in a Production environment, extra disks can be added or removed without a need of rebooting the Linux machine. How to add a new disk : Once you have present your new disk or Lun to the RHEL OS run : # echo "- - -" >/sys/class/scsi_host/host#/scan The "- - -" is used for the bus channel, Target Id and Lun. Check the /var/log/messages  to find the new device name or by checking the /proc/partitions file. # tail -f /var/log/messages # cat /proc/partitions If your new disk name  is /dev/sdb ,   get more information about it by running # fdisk -l /dev/sdb