On Wed, Feb 17, 2010 at 2:49 PM, Mrohs, Ray <[email protected]> wrote: > Hi, > We are running SLES10 and WebSphere on 1 IFL and 2G storage. These > bursts of activity seem to happen every few hours. > Is occasional swapping in the thousands too high if its going to VDISK? > What can cause the high 'wa' values? Our info is limited since this is a > test partition with no VM performance monitoring (yet). > Thanks for any insight!
The "wa" column is % of time waiting for I/O. Your vmstat data shows swapping, so my guess is that you're swapping to real disk and the process is in I/O wait for the swap-in. So the virtual machine is too small for this workload. Since this spike happens frequently, it could be the JVM Garbage Collection going through the entire JVM heap and force all pages to be swapped in. Your page cache is rather large for a WAS workload, might be a good thing to lower the swappiness. Increasing the virtual machine size or adding VDISK for swap would help, but can't say whether that fits without seeing z/VM data. Did I already mention Performance Monitor? Oh, you did ;-) -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
