Hello all. I have a centos 4.4 box (2.6.9-42.0.10.ELsmp) with 7gig of ram that doesn't seem to be using swap (also 7gig now). I say "seem" because I've noticed ram utilization run around 95% (with oracle and friends running) and then firing up a couple apps to use that last 5% will stop the machine dead in it's tracks. I ran across some reading[0] about /proc/sys/vm/swappiness and how it affects the kernels decisions when dealing with swap, but it's not all that clear to me whether this is the source of the problem. It seems like the kernel just isn't using swap at all. I've double checked my swap partition in fstab, ran mkswap again, double checked it's availability with vmstat -s but still it's just not getting used. Sunday, the box died around 3am and sar seems to show memory use on the rise right up till it hurled[1] (I just stuck another gig in the box monday, so sar only shows 6gig on sunday) Anyone know whats up with this? PS: swap is an LVM partition. Thanks Thomas [0] - http://lwn.net/Articles/83588/ [1] - sar -A 12:00:01 AM kbmemfree kbmemused %memused kbbuffers kbcached kbswpfree kbswpused %swpused kbswpcad ... 02:40:01 AM 197656 5909384 96.76 203308 4066344 16383992 0 0.00 0 02:50:01 AM 191728 5915312 96.86 203320 4066400 16383992 0 0.00 0 03:00:01 AM 185584 5921456 96.96 203336 4067132 16383992 0 0.00 0 03:10:01 AM 185712 5921328 96.96 203344 4067872 16383992 0 0.00 0 Average: 191895 5915145 96.86 203221 4063819 16383992 0 0.00 0 12:00:01 AM pswpin/s pswpout/s ... 02:00:01 AM 0.00 0.00 02:10:01 AM 0.00 0.00 02:20:01 AM 0.00 0.00 02:30:01 AM 0.00 0.00 02:40:01 AM 0.00 0.00 02:50:01 AM 0.00 0.00 03:00:01 AM 0.00 0.00 03:10:01 AM 0.00 0.00 Average: 0.00 0.00 -- Flambeau Inc. Technology Center - Baraboo, WI Email : tblader at flambeau.com Keyserver: http://pgp.mit.edu KeyID: 0x00E9EC2C
On 4/10/07, tblader <tblader at flambeau.com> wrote:> Hello all. > I have a centos 4.4 box (2.6.9-42.0.10.ELsmp) with 7gig of ram that > doesn't seem to be using swap (also 7gig now). I say "seem" because > I've noticed ram utilization run around 95% (with oracle and friends > running) and then firing up a couple apps to use that last 5% will > stop the machine dead in it's tracks. >How do you have your swap space allocated? Is it all 1 big 7G chunk, or broken up across disks somewhat? There used to be a limitation with having a single swap partition over 2G in size. I'm not certain if that still applies or not. If you really do require 7G of swap space, you'll probably see a benefit to keeping it spread across multiple spindles in 1-2G chunks. This will allow some sane system handling when swap usage is required, and it'll be able to essentially raid the swap space, for lack of a better description. -- During times of universal deceit, telling the truth becomes a revolutionary act. George Orwell
tblader wrote:> Hello all. > I have a centos 4.4 box (2.6.9-42.0.10.ELsmp) with 7gig of ram that > doesn't seem to be using swap (also 7gig now). I say "seem" because > I've noticed ram utilization run around 95% (with oracle and friends > running) and then firing up a couple apps to use that last 5% will > stop the machine dead in it's tracks. >What architecture is this beast? -- Cheers John -- spambait 1aaaaaaa at coco.merseine.nu Z1aaaaaaa at coco.merseine.nu Please do not reply off-list
Linux uses all ram for file caching if applications don't use it. That's how it works. If you aren't using swap and your mahcine is running fine everything's cool tblader wrote:> Hello all. > I have a centos 4.4 box (2.6.9-42.0.10.ELsmp) with 7gig of ram that > doesn't seem to be using swap (also 7gig now). I say "seem" because > I've noticed ram utilization run around 95% (with oracle and friends > running) and then firing up a couple apps to use that last 5% will > stop the machine dead in it's tracks. > > I ran across some reading[0] about /proc/sys/vm/swappiness and how it > affects the kernels decisions when dealing with swap, but it's not > all that clear to me whether this is the source of the problem. > It seems like the kernel just isn't using swap at all. > > I've double checked my swap partition in fstab, ran mkswap again, > double checked it's availability with vmstat -s but still it's > just not getting used. Sunday, the box died around 3am and sar > seems to show memory use on the rise right up till it hurled[1] > (I just stuck another gig in the box monday, so sar only shows > 6gig on sunday) > > > Anyone know whats up with this? > PS: swap is an LVM partition. > > Thanks > Thomas > > > > [0] - http://lwn.net/Articles/83588/ > [1] - sar -A > 12:00:01 AM kbmemfree kbmemused %memused kbbuffers kbcached kbswpfree > kbswpused %swpused kbswpcad > ... > 02:40:01 AM 197656 5909384 96.76 203308 4066344 > 16383992 0 0.00 0 > 02:50:01 AM 191728 5915312 96.86 203320 4066400 > 16383992 0 0.00 0 > 03:00:01 AM 185584 5921456 96.96 203336 4067132 > 16383992 0 0.00 0 > 03:10:01 AM 185712 5921328 96.96 203344 4067872 > 16383992 0 0.00 0 > Average: 191895 5915145 96.86 203221 4063819 > 16383992 0 0.00 0 > > > 12:00:01 AM pswpin/s pswpout/s > ... > 02:00:01 AM 0.00 0.00 > 02:10:01 AM 0.00 0.00 > 02:20:01 AM 0.00 0.00 > 02:30:01 AM 0.00 0.00 > 02:40:01 AM 0.00 0.00 > 02:50:01 AM 0.00 0.00 > 03:00:01 AM 0.00 0.00 > 03:10:01 AM 0.00 0.00 > Average: 0.00 0.00 > > > >-- My "Foundation" verse: Isa 54:17 No weapon that is formed against thee shall prosper; and every tongue that shall rise against thee in judgment thou shalt condemn. This is the heritage of the servants of the LORD, and their righteousness is of me, saith the LORD. -- carpe ductum -- "Grab the tape" CDTT (Certified Duct Tape Technician) Linux user #322099 Machines: 206822 256638 276825 http://counter.li.org/