KVM performance issue with Isilon

Question

Hello Team, We presented NFS export to Linux machine, I have created a virtual machine on top of Linux machine Recently we happen to test network performance for one of the KVM, but the linux KVM guests network performance is slower than host, KVM gives me the speed of 13Mb/s where as the Host gives me the spped of 75Mb/s, in 1 Gb link If I look at the dumps the difference that jumps out at me is that halfway, through the tcpdump file the VM NFS session has a window size of around 610, or so, where the host NFS session has a window size of 28665 or so. Is this problem related to Isilon? because Host is giving the required performance, where as KVM is reduced to 1/4 speed

sluetze · Answer

Hi pradeeps24,normally when you have multiple Clients (and the host is a Client in this configuration) and they behave differently while using the same paths and protocols the cause is in the Client check: http://nfs.sourceforge.net/nfs-howto/ar01s05.html for multiple possibilities where you can configure the nfs buffers, window size etc.good luck-- sluetze

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