[borland]

Yep. At a previous job we had a file server that we published Windows build output to.

There were about 1000 copies of the same pre-requisite .NET and VC++ runtimes (each build had one) and we only paid for the cost of storing it once. It was great.

It is worth pointing out though, that on Windows Server this deduplication is a background process; When new duplicate files are created, they genuinely are duplicates and take up extra space, but once in a while the background process comes along and "reclaims" them, much like the Hyperspace app here does.

Because of this (the background sweep process is expensive), it doesn't run all the time and you have to tell it which directories to scan.

If you want "real" de-duplication, where a duplicate file will never get written in the first place, then you need something like ZFS

[p_ing]

Both ZFS and WinSvr offer "real" dedupe. One is on-write, which requires a significant amount of available memory, the other is on a defined schedule, which uses considerably less memory (300MB + 10MB/TB).

ZFS is great if you believe you'll exceed some threshold of space while writing. I don't personally plan my volumes with that in mind but rather make sure I have some amount of excess free space.

WinSvr allows you to disable dedupe if you want (don't know why you would) where as ZFS is a one-way street without exporting the data.

Both have pros and cons. I can live with the WinSvr cons while ZFS cons (memory) would be outside of my budget, or would have been at the particular time with the particular system.

[sterlind]

hey, it's defrag all over again!

(not really, since it's not fragmentation, but conceptually similar)