Question: How to enable the automatic extension capability for a thin LVM volume?
By default, the automatic extension is set to ‘100‘
# grep thin_pool_autoextend_threshold /etc/lvm/lvm.conf # Configuration option activation/thin_pool_autoextend_threshold. # thin_pool_autoextend_threshold = 70 thin_pool_autoextend_threshold = 100
These settings imply the function has been disabled:
# Configuration option activation/thin_pool_autoextend_threshold. # Auto-extend a thin pool when its usage exceeds this percent. # Setting this to 100 disables automatic extension.
To enable the automatic extension, change both the ‘thin_pool_autoextend_percent‘ and ‘thin_pool_autoextend_threshold‘ settings:
thin_pool_autoextend_threshold = 70 thin_pool_autoextend_percent = 20
Which means whenever a pool exceeds 70% usage, it will be extended by another 20%. For a 1G pool, using 700M will trigger a resize to 1.2G. When the usage exceeds 840M, the pool will be extended to 1.44G, and so on.