In a virtualized environment, the block devices on the I/O do-
main can be provided to guest domains by the virtual block de-
vice (VBD). As the VBD incurs low latency and no network access
is involved in accessing data, VBD has been used for storing in-
termediate data of data-intensive applications such as MapReduce.
To accelerate the performance further, SSD can be considered as
a backing device of the VBD because SSD outperforms HDD by
several orders of magnitude. However, the TRIM command that
plays an important role in space management of SSD has not been
discussed nor handled properly in the virtualized environment.
In this paper, we clarify the challenges in supporting the TRIM
command in the VBD configuration and propose a novel file oper-
ation, called FTRIM (file trim). The FTRIM bridges the semantic
gaps among key components of VBD and makes them to be aware
of the file deletion in the guest domain. As a result, the each com-
ponent of VBD can utilize the space of the deleted files, and the
SSD in the I/O domain can be notified by the TRIM command.
Our evaluation with a prototype shows that the proposed approach
achieves up to 3.47x speed-up and sustains the improved perfor-
mance in the consolidated VM environment.