Big Picture of the LVM

Advantages:

• Filesystems can span disks, so size is not limited by capacity of physical disks.
• Can expand filesystems on the fly.
• Can add additional disks to existing pool of disk space (VG).
• Can mirror important data on multiple physical disks for redundancy.
• Can "export" an entire VG so that all disks in the VG can be easily physically disconnected, moved to another machine, and "imported".

Limitations:

• Must reducevg when removing disk.
• When a single disk in a VG dies, the whole VG is affected.
• "Brick Wall" between VGs - LVs can't cross VG boundary.
• Cannot shrink filesystems.

• Configuring for performance or flexibility vs. reliability or fault-tolerance.
• Strategy: Define adequate but not huge filesystems, leaving pool of free storage for later assignment.
• Seperate out data categorically onto different VGs, so that an OS upgrade will not touch user data, or so that user data can be easily moved to another machine.