On Miércoles, 5 de Enero de 2011 21:25:41 Gordan Bobic escribió: > The point is that the offline dedup is actually twice as expensive, and > the hashing part is nowhere nearly expensive as disk I/O. Disk I/O is > very limited today, compared to CPU time. And my point is: > But there are people who might want to avoid temporally the extra cost > of online dedup, and do it offline when the server load is smaller. In fact, there are cases where online dedup is clearly much worse. For example, cases where people suffer duplication, but it takes a lot of time (several months) to hit it. With online dedup, you need to enable it all the time to get deduplication, and the useless resource waste offsets the other advantages. With offline dedup, you only deduplicate when the system really needs it. And I can also imagine some unrealistic but theorically valid cases, like for example an embedded device that for some weird reason needs deduplication but doesn't want online dedup because it needs to save as much power as possible. But it can run an offline dedup when the batteries are charging. It's clear to me that if you really want a perfect deduplication solution you need both systems. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
