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