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On Mon, 2011-01-17 at 16:23 -0800, Grant wrote: |
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> > I think the idea is never use swap if possible, but in a case where |
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> > you don't have swap space or run out of swap space I think it's still |
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> > possible to lose data. |
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> |
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> Isn't swap just an extension of system memory? Isn't adding 4GB of |
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> memory just as effective at preventing out-of-memory as dedicating 4GB |
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> of HD space to swap? I can understand enabling swap on a laptop or |
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> other system with constrained memory capacity, but doesn't it make |
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> sense to disable swap and add memory on a 24GB server? |
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> |
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> Is swap basically a way to save money on RAM? |
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> |
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> - Grant |
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> |
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No swap contains pages from memory that have not been accessed for |
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awhile so they can be stored elsewhere freeing ram for actual active |
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pages. When they need to be accessed, they have to be swapped back in, |
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and often something swapped back out to make room for it. |
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And for those with gigabytes of swap, keep in mind that the majority of |
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processors can only access up to 32 x 2G swapfiles under linux, so 4G is |
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only going to be half used. Some processors are only able to handle |
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very small swapfiles, whilst amd opterons can handle very large ones. |
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It does appear however that some distros (redhat and suse ?) have |
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modified something to allow larger swap sizes on 64bit systems, but via |
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google it seems very muddy at the moment. |
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On my mostly 32bit systems its only the opterons (which are running |
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64bit systems) that can access more than 2G swap using gentoo-sources |
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kernels when I tested late last year. |
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BillK |
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-- |
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William Kenworthy <billk@×××××××××.au> |
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Home in Perth! |
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