Welcome to IBM Aspera Sync, a software application that provides high-speed and highly scalable
multi-directional, file-based replication and synchronization. Aspera Sync is designed
to fill the performance gap of uni-directional file synchronization tools like rsync,
which are often slow for synchronizing large files and large sets of files over the WAN.
Additionally, Aspera Sync extends the capability of uni-directional synchronization
tools with full support for synchronization that is bi-directional and
multi-directional. Unlike traditional synchronization tools, Aspera Sync offers the
following key capabilities:
- Utilizes high-speed Aspera FASP transport for moving data at maximum speed over the WAN,
while traditional synchronization tools are built on TCP. Aspera Sync transfers new
data between remote hosts at full bandwidth capacity, regardless of round-trip delay
and packet loss, and does not degrade in performance for large file sizes.
- Compares against a local snapshot, thereby avoiding the process of making a comparison
against the remote file system over the WAN (which can be slow). Most traditional
tools, such as rsync, determine what to transfer by comparing the local and remote
file system over the WAN.
- Recognizes file system changes (such as moves and renames) and propagates
these changes to peers. Traditional tools treat these operations as deletion of old
data and then recreate or retransfer the new data, which can lead to costly data
copying over the WAN.
- Supports bi-directional and multi-directional synchronization topologies, where files are
changing on multiple nodes. For a bi-directional synchronization, Sync runs with a
bi-directional option. For a multi-directional synchronization, one session is run
for each peer to remain synced. Any topology that has an acyclic graph topology
between peers is supported.
- Uses file system notifications for change notification, when available.
- Monitors file contents and waits for files to be stable (no longer changing in md5sum) before transferring. The wait period is configurable and is designed to avoid transferring only partially complete files.
Aspera Sync is a command-line program called async that, like rsync, uses an SSH
connection to establish connectivity with its remote peers and is spawned as an SSH
subsystem binary on the remote system. The program can be run one time or periodically
(through a cron tab scheduled job) on file systems that do not provide asynchronous
change notification, or in a continuous mode on file systems that do support
asynchronous change notification. Sync is designed to process files and transfer new
data in a continuous pipeline for maximum speed, even when running in scan-only mode
(when no file system change notification is available).