[teilo]

Why are enterprise SANs so good at dedupe, but filesystems so bad? We use HPE Nimble (yeah, they changed the name recently but I can't be bothered to remember it), and the space savings are insane for the large filesystems we work with. And there is no performance hit.

Some of this is straight up VM storage volumes for ESX virtual disks, some direct LUNs for our file servers. Our gains are upwards of 70%.

[growse]

Totally naive question: is this better than you get than simply compressing?

It's not 100% clear to me why explicit deduping blocks would give you any significant benefit over a properly chosen compression algorithm.