On 04/14/10 19:51, Richard Jahnel wrote:
This sounds like the known issue about the dedupe map not fitting in ram.
Indeed, but this is not correct:
When blocks are freed, dedupe scans the whole map to ensure each block is not
is use before releasing it.
That's not correct.
dedup uses a data structure which is indexed by the hash of the contents
of each block. That hash function is effectively random, so it needs to
access a *random* part of the map for each free which means that it (as
you correctly stated):
... takes a veeery long time if the map doesn't fit in ram.
If you can try adding more ram to the system.
Adding a flash-based ssd as an cache/L2ARC device is also very
effective; random i/o to ssd is much faster than random i/o to spinning
rust.
- Bill
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