Original sentence: Active (real-time) file system replication is usually implemented by distributing updates of a virtual block device to several disks.Alternatively, updates to a block device can be replicated (that is, distributed) over a computer network.An example of this kind of replication is the DRBD module for Linux.The most popular method for filesystem replication is RAID which is typically limited to locally-connected disks only.This has the advantage that the replication slaves can be located in physically distant locations, to avoid damage done by, and improve availability in case of local failures or disasters.This way, any filesystem supported by the operating system can be replicated without modification, as the file system code works on a level above the block device layer
Edited sentence: Active (realtime) file system replication can be obtained by using, for example, the block level replication Linux kernel module drbd for Linux.Drbd makes high available service (disambiguation)'s possible even if large filesystems are used because drbd features intelligence when Synchronization is performed.NetVault:Replicator is an example of a real-time solution that provides continuous byte-level data replication for heterogeneous operating systems.The file replication service is another example