On 03/14/2014 03:06 PM, Matthew Eaton wrote:
zero_buffers and buffer_compres_percentage=100 are essentially the same
thing, for both cases it writes buffers just fill of zeroes. So I'm not sure
what you were expecting here since you don't think it works as it should?
If you have both zero_buffers and scramble set, then the result will be a
bit less compressible. The goal of scramble_buffers is to defeat basic
dedupe attempts. So even if you don't fully refill your buffers every time,
the blocks will be a bit different.
--
Jens Axboe
Hmm, I was assuming that scramble_buffers shouldn't have any effect
since it's scrambling all zeros. Is scramble_buffers inserting random
data even with zero_buffers set?
scramble_buffers tells fio to randomly insert some data in the buffer.
It's not a full overwrite or anything like that, just some basic garbage
for each 512b to prevent naive compression/dedupe.
--
Jens Axboe
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