3.3. Block Discard — Enhanced Support for Thinly Provisioned LUNs and SSD Devices
Filesystems in Red Hat Enterprise Linux 6 use the new block discard feature to allows a storage device to be informed when the filesystem detects that portions of a device (also known as blocks) are no longer in active use. While few storage devices feature block discard capabilities, newer solid state drives (SSDs) utilize this feature to optimize internal data layout and invoke proactive wear levelling. Additionally, some high end SCSI devices use block discard information to help implement thinly provisioned LUNs.