AIX LVM – Logical Volume Manager Introduction
AIX LVM has the unique capability which distinguish from other UNIX Operation Systems. LVM has physical component which put individual or grouped together to create logical devices to store data by using AIX LVM level commands to make use of internal or external storage.
Physical Volumes (PV’s) :-
Physical Volume is an actual physical disk which is attached in AIX partition. In operating system the physical disk would be shown as hdisk and it starts with hdisk0 and so on as next sequence number along with prefix hdiskX if you add any new disk. The disk can be assign through internal RAID controller (SAS/SCSI) or externally and the actual external storage gets connected with AIX OS by using HBA’s.
Each and every physical volume would have their own physical identifier number that is PVID and PVID is unique if by change any of the two physical volume having the same PVID would result unpredictable errors.
Volume Group (VG) :-
The volume group created by using one or more than one physical volumes. While creating a volume group we have to specify the name of the volume group. Based on the number of physical volumes and number of logical volume and physical partition limitation the volume group has been categorized such that normal vg, big vg and scalable volume group.
Physical Partition (PP’s) :-
A smallest logical unit in a volume group is been called as physical partition. If you are using a RAW hdisk there is no need to do any partition otherwise, we have to make a physical partition. Physical partition size we have to give as on input while creating volume group because PP size cannot be change online if you wish to change the PP size needs to destroy the volume group and the by default PP size is 4 MB and the max PP’s per PV is 1016 by default.
Logical Partition (LP’s) :-
Logical partition is associated with physical partition in actual logical partition is not an independent also each and every physical partition has its own logical partition.
Logical Volume (LV) :-
Logical volume is a character special device which created by using one or more than one physical partition and it’s associated with a logical partitions. In usability point of view Logical volumes can be used as RAW or by using logical volumes file systems can be created.
File System (FS) :-
File system is an actual mount directory which is associated with a logical volume.