Active Storage provides an opportunity for reducing the amount of data movement between storage and compute nodes of a parallel filesystem such as Lustre, and PVFS. It allows certain types of data processing operations to be performed directly on the storage nodes of modern parallel filesystems, near the data they manage. This is possible by exploiting the underutilized processor and memory resources of storage nodes that are implemented using general purpose servers and operating systems. In this paper, we present a novel user-space implementation of Active Storage for Lustre, and compare it to the traditional kernel-based implementation. Based on microbenchmark and application level evaluation, we show that both approaches can reduce the network traffic, and take advantage of the extra computing capacity offered by the storage nodes at the same time. However, our user-space approach has proved to be faster, more flexible, portable, and readily deployable than the kernel-space version.