Date: Tue, 22 Jul 2014 12:23:05 -0400 From: Daniel Corbe <corbe@corbe.net> To: Arthur Chance <freebsd@qeng-ho.org> Cc: FreeBSD-Questions <freebsd-questions@freebsd.org> Subject: Re: How much swap space for a 32 GB RAM system? Message-ID: <ygfmwc1e51y.fsf@corbe.net> In-Reply-To: <53CE8BB8.7030303@qeng-ho.org> (Arthur Chance's message of "Tue, 22 Jul 2014 17:05:12 %2B0100") References: <53CE8BB8.7030303@qeng-ho.org>
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Arthur Chance <freebsd@qeng-ho.org> writes: > I'm getting a new machine with 32 GB of memory. The old "twice > physical memory" sizing seems ridiculous, so how big should I make > swap? Do I even need swap with this much memory? The rule of thumb is 1.5x physical RAM but that's an antiquated notion. With that much RAM in your system, you shouldn't ever need swap. But you want to build in a "I need to add more RAM to this system" buffer so that you don't run out of memory and crash your application if your size requirements happen to change. So here's what I do: 2GB of swap. Then I set my monitoring system to alert as soon as I get below 97% available swap space. 97% is a good number because some things will end up in swap no matter how you tune your system. Also make sure kern.ipc.shm_use_phys=1. -Daniel
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