The wikipedia artile:
includes reference tp :
This seems provide good explanation of LVM, with various images and examples :-)
With Linux, the LVM is structured in three elements:
Volumes: physical and logical volumes and volume groups
Extents: physical and logical extents
Device mapper: the Linux kernel module
vgscan - Scan all disks for volume groups and rebuild caches.
Am NON-technical, so my guess
Lines 99 to 103 show another quite interesting/important command — vgscan scans all disks for volume groups and rebuilds caches. Here is the rationale for line 99: I am using an external USB (Universal Serial Bus) HDD (Hard Disk Drive) for this article i.e. what can be seen in line 13 to 15 are physical partitions on this HDD. Since I turn this HDD off over night (I went to bed between lines 98 and 99 i.e. turned off the external HDD and subnotebook), I need to issue vgscan in order to rescan for VGs — otherwise only vg0 on my subnotebook would be known to the system.
, reads as though cache
refers to data-block addresses stored in cache=memory needing be refreshed from time to time so as to keep track of where everything is. Add a new computer with HD's required LVM learning where in new pc all the components were, then storing their address details in memory to enable speedy access.
Guess, wiping the cache means replacing current LV Memory using new scan results of where everything is stored.