Mailinglist Archive: opensuse (1239 mails)

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Re: [opensuse] How Much Swap?
  • From: Greg Freemyer <greg.freemyer@xxxxxxxxx>
  • Date: Wed, 26 Jun 2013 10:34:53 -0400
  • Message-id: <>
On Wed, Jun 26, 2013 at 10:12 AM, Lew Wolfgang <wolfgang@xxxxxxxxxxxxxxx> wrote:
Hi Folks,

Back in the '80s we configured swap space to be 1.5 x RAM
as a rule of thumb. But I'm configuring 6 boxes now that
contain 64-GB of RAM and I'm wondering if swap should be
anything close to 96-GB. The boxes have only 128-GB of
SSD for the operating system, so I'd like to minimize swap
as much as possible.

As background, these devices will be used as dedicated
data acquisition devices. They will pump data from
four Gig-E Ethernet ports and store it all in a 24-disk
RAID-6 array. Preliminary measurements show we should
be able to maintain continuous throughput until the RAID
is full.

So, any opinions on swap size in relation to RAM?



As others have said, the guidelines are gone. It is now application
specific. I default to 1x just so that I don't have to worry about
ever running out. Effectively for most of my work loads if I ever use
as much swap as ram, then my computer is running too slow to be
effectively functional.

fyi: I built a machine with 128GB of RAM a year ago. I had Java apps
that allowed me to set their max memory usage. I set them to
cumulatively be 96 GB and used the last 32 GB for cache and other
system programs. I only setup a 16GB swap as I recall. That would
allow rarely used code pages to be pushed to swap and use that ram for
cache instead. Lots of cache can be a great thing for some workloads.

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