Date: Tue, 28 Sep 2010 16:46:28 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Willem Jan Withagen <wjw@digiware.nl> Cc: stable@freebsd.org, fs@freebsd.org Subject: Re: Still getting kmem exhausted panic Message-ID: <4CA1F1B4.1020700@icyb.net.ua> In-Reply-To: <4CA1ECCC.4070801@digiware.nl> References: <4CA1D06C.9050305@digiware.nl> <20100928115047.GA62142@icarus.home.lan> <4CA1ECCC.4070801@digiware.nl>
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on 28/09/2010 16:25 Willem Jan Withagen said the following: > Well advises seem to vary, and the latest I understood was that > 8.1-stable did not need any tuning. (The other system with a much older > kernel is tuned as to what most here are suggesting) > And I was shure led to believe that even since 8.0 panics were no longer > among us...... Well, now you have demonstrated yourself that it is not always so. >> vm.kmem_size >> vfs.zfs.arc_max > > real memory = 12889096192 (12292 MB) > avail memory = 12408684544 (11833 MB) > > So that prompts vm.kmem_size=18G. > > Form the other post: >> As to arc_max/arc_min, set them based your needs according to general >> ZFS recommendations. > > I'm seriously at a loss what general recommendations would be. Have you asked Mr. Google? :) - http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide Search for "Memory and Dynamic Reconfiguration Recommendation" - http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Limiting_the_ARC_Cache Short version - decide how much memory you need for everything else but ZFS ARC. If autotuned value suits you, then you don't need to change anything. > The other box has 8G > loader.conf: > vm.kmem_size="14G" # 2* phys RAM size for ZFS perf. > vm.kmem_size_scale="1" No need to set both of the above. vm.kmem_size overrides vm.kmem_size_scale. > vfs.zfs.arc_min="1G" > vfs.zfs.arc_max="6G" > > So I'd select something like 11G for arc_max on a box with 12G mem. -- Andriy Gapon
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