[dm-crypt] Bad performance with software RAID5 and LUKS encryption

Philipp Wendler ml at philippwendler.de
Tue Jul 5 17:22:22 CEST 2011


Hi,

Am 05.07.2011 15:30, schrieb Jens Wahnes:
> Philipp Wendler wrote:
>
>> [1] All speed measurements were done with several runs of
>> dd if=/dev/zero of=DEV bs=100M count=100
>
> Did you consider using another block size?

So far I tested with a large block size only, because I was expecting a 
bad performance for small block sizes due to the raid5 anyway.

But I have now run a series of tests with 4K, 1M and 10M. Block size 
indeed affects the performance (although not as much as I would have 
expected), but the difference for with/without encryption still remains 
as large as before:

without encryption: 150-180 MB/s
with encryption: 30-40 MB/s

Greetings, Philipp


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