On Thu, Jul 1, 2010 at 04:33, Lutz Schumann <presales@xxxxxxxxxxxxxxxxxx> wrote:
> Hello list,
> I wanted to test deduplication a little and did a experiment.
> My question was: can I dedupe infinite or is ther a upper limit ?
> So for that I did a very basic test.
> - I created a ramdisk-pool (1GB)
> - enabled dedup and
> - wrote zeros to it (in one single file) until an error is returned.
I don't know about the rest of your test, but writing zeroes to a ZFS
filesystem is probably not a very good test, because ZFS recognizes
these blocks of zeroes and doesn't actually write anything. Unless
maybe encryption is on, but maybe not even then.
I'd write a little program that initializes 128k of memory to a
particular pattern, then writes it to disk until it gets ENOSPC (or
some other error code, I suppose). That should force the first block
to actually be written, and all the others to point to it.
> During the experiment I could nicely see:
> - that performance on ramdisk is CPU bound doing ~125 MB /sec per Core.
Ouch! That's all?
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