Date: Mon, 21 Sep 2015 13:50:38 +0100 From: krad <kraduk@gmail.com> To: Quartz <quartz@sneakertech.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: ZFS cpu requirements, with/out compression and/or dedup Message-ID: <CALfReyc1DcNaRjhhhx%2B4swF2hbfuAd2tWv2xpjWtfqcDoxHUBw@mail.gmail.com> In-Reply-To: <55FD9A2B.8060207@sneakertech.com> References: <CAEW%2BogbPswfOWQzbwNZR5qyMrCEfrcSP4Q7%2By4zuKVVD=KNuUA@mail.gmail.com> <55FD9A2B.8060207@sneakertech.com>
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"It's also 'permanent' in the sense that you have to turn it on with the > creation of a dataset and can't disable it without nuking said dataset. " This is completely untrue, there performance issues with dedup are limited to writes only, as it needs to check the DDT table for every write to the file system with dedup enabled. Once the data is on the disk there is no overhead, and in many cases a performance boost as less data on the disk means less head movement and its also more likely to be in any available caches. If the write performance does become an issue you can turn it off on that particular file system. This may cause you to no longer have enough capacity on the pool, but then pools are easily extended.
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