<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none"></style> </head> <body dir="ltr" style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;"> hi all, All my vSphere (ESXi5.1) hosts experience a big spike in latency every hour or so. I tested on Infiniband iSER and SRP and also 4Gbit FC and 8GBit FC. All exhibit the same behavior so I don't think its the connection that is causing this. When I modify the arc_shrink_shift 10 (192GB Ram in the System) it helps a bit, the spikes are still with the same regularity but latency peaks at about ~5000ms for the most part. if I leave arc_shrink_shift at the default value they can be higher - up to 15000ms. Looking at the latency as seen from the vSphere hosts the average is usually below 1ms for most datastores. Any ideas what can cause this or what can be done to fix? br, Rune </body> </html>