[opensuse] Re: How Much Swap?

On Wed 26 Jun 2013 10:34:53 AM CDT, Greg Freemyer wrote:

On Wed, Jun 26, 2013 at 10:12 AM, Lew Wolfgang 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?

Thanks, Lew

Lew,

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.

Greg Hi If needed there is always the zram kernel module? http://en.wikipedia.org/wiki/ZRam

-- Cheers Malcolm °¿° (Linux Counter #276890) openSUSE 12.3 (x86_64) Kernel 3.7.10-1.16-desktop up 1 day 14:15, 5 users, load average: 0.25, 0.14, 0.10 CPU AMD Athlon(tm) II P360@2.30GHz | GPU Mobility Radeon HD 4200 -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org