The Post Process Advantage
Shortest backup window via post-process data deduplication
ExaGrid employs post-process deduplication, which allows the backups to write directly to disk at disk speed. This produces a faster backup and shorter backup window. The rationale here is to defer the compute-intensive process until after the backup has landed so as not to impact the time it takes to perform the backup.
Another approach in the market is inline deduplication, which deduplicates data on the fly, before it lands on the disk. Because inline deduplication can potentially cause a bottleneck at the point where data is streaming into the backup appliance, inline deduplication can result in slower performance and a longer backup window. Proponents of inline deduplication often argue that their approach requires less disk and is therefore less expensive. However, because inline deduplication must rely on faster and more expensive processors--and more memory--in order to avoid being prohibitively slow, any cost differences in the amount of disk used are overcome by the need for more expensive processors and memory.