Date: Wed, 18 Oct 2023 10:56:32 +0100 From: void <void@f-m.fm> To: freebsd-fs@freebsd.org Subject: Re: performance impact of various compression schemes on a zvol Message-ID: <ZS-r0Olf9Dl4NbcY@int21h> In-Reply-To: <c9f1b0a3-2cf8-4209-89a8-77e9b501e394@gmx.at> References: <ZS8Lt5wGKc6vIRrf@int21h> <c9f1b0a3-2cf8-4209-89a8-77e9b501e394@gmx.at>
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On Wed, Oct 18, 2023 at 09:21:29AM +0200, infoomatic wrote: >On 18.10.23 00:33, void wrote: >>What's the perfomance penalty on zvols of compression? >>The impact on the host? > >This totally depends on your data. I did some tests on our mailserver, >and for us it boiled down to: > >*) use lz4 if performance is very important, and compression rate not so >much. We found that the impact of lz4 is so fast that our workloads were >quite faster than any test without compression, so I would say you can >set lz4 in any way (lz4 is very fast on detecting incrompressible data) > >*) use between zstd-6 and zstd-9 (not too much difference in our tests) >if you want a nice balance where performance is not too much affected >and we reach a nice level of compression, however, of course your >definition of "maximum performance penalty" may be different. > >You could check out lzbench. Thanks everyone, this is exactly the type of info I was looking for. In terms of data used within the vm, I'd guess 70% of the space currently used is uncompressible multimedia. I'll stay with lz4 (when file-backed the vm was on a lz4 vdev. I'll set the vol to use lz4). There is no filesystem compression within the vm as it's a linux guest which pre-dates zfs use within linux). --
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