Fig. 6. Block State Transition
erase blocks. Only blocks in the Checkpointed Zone serve
as candidates for garbage collection in LightTx, because
the transaction information in both the Available and
Unavailable Zones is protected for transaction state identification
during recovery. Since the blocks in Available and
Unavailable Zones, which are used for recent allocation,
are unlikely to be chosen for garbage collection, the
garbage collection overhead of LightTx is nearly the
same as that of conventional FTLs. LightTx’s overhead is
rather low compared to previous embedded transaction
designs [5], [4] because the previous designs have extra
restrictions on garbage collection (e.g., forced garbage
collection of aborted pages in SCC [4], prevented garbage
collection in BPCC [4] on blocks that have experienced
aborts since the last committed version).
In addition to garbage collection, LightTx puts few
restrictions on wear leveling. For dynamic wear leveling,
LightTx has no restrictions. For static wear leveling, no
flash blocks in the Available and Unavailable Zones are
selected for wear leveling.