PCoIP Packet Loss? Don’t Blame the Network!

Several months ago I was called into a new customer to diagnose some odd behavior in their VMware View environment. The organization was struggling with constant disconnects and generally poor performance on their View desktops. When users weren’t being randomly disconnected from their desktops, the users experienced lag when dragging windows between multiple monitors, ‘choppy’ graphics/video, and slow application launching. The problems occurred with local and remote users (both WAN and LAN could be involved).  The customer had done some troubleshooting, worked with VMware Support and the … [Read more...]

Troubleshooting Slow Logon to VMware View Desktops

I did a bit of troubleshooting today for a customer who was experiencing very slow logon times to VMware View desktops running Windows XP.  I suspect the problem is a fairly common one so I thought I might share my troubleshooting methodology and the solution that got the login time back to normal.  Following a rigid methodology may be overkill for many troubleshooting situations.  If you strongly suspect a root cause to a problem, check the solution before digging in to analytic troubleshooting.  A little bit of Googling may eventually get you to an answer for a particular problem, but having … [Read more...]

CPU Ready Revisted – Quick Reference Charts

I've written in the past about how high CPU Ready values can cause performance problems in VMware vSphere environments.  For those who don't know, CPU Ready is a measure of the amount of time that a guest VM is ready to run, but the VMware ESXi CPU Scheduler on the host is not able to immediately allocate cycles to the guest because it is busy doing work for other VM's.  CPU Ready values are exposed through ESXTOP and in the vSphere Client. I'm often called into customer environments to do performance troubleshooting, and CPU Ready is one of the first performance measurements I check my … [Read more...]

iSCSI Bug – Traffic Routed Out Wrong Interface – Update

One of my most popular posts to date has been 'vSphere 5 Networking Bug Affects Software iSCSI' with some 20,000 page views and a bunch of comments.  The problem is a bug that causes vmkernel traffic (including iSCSI) to be sent out the unused/inactive/null NIC on a vSwitch with a manual failover order and Active and Unused vmnics.  It still appears that the issue I covered is affecting customers - we just had a new Clearpath customer call for help with this very issue.  VMware's KB on the issue … [Read more...]

Lag When Dragging a Window Between Monitors in VMware View

I've had several customers ask me for help with the VMware View environment recently, as their users were complaining about performance issues when dragging a window between monitors in a multi-monitor VMware View setup.   Performance was otherwise acceptable on the View desktops.  I recommended several troubleshooting and remediation steps to get windows to stop slowing down when dragging between monitors or "catching" on the border between the two screens, including: Review the "Multimonitor PCoIP sessions are not displayed as expected KB article" (1030566) from VMware. Monitor PCoIP … [Read more...]

vSphere 5 Networking Bug #2 Affects Management Network Connectivity

On Wednesday, I wrote about a VMware vSphere 5 networking bug that caused issues with iSCSI networking.  That bug, described in VMware KB 2008144 caused vmk traffic to be sent over the unused vmnic uplink in a team where there is an unused uplink and an explicit failover policy present.  See the diagram below to better understand what was going on there…. The second bug vSphere 5 networking bug I experienced was similar to the first: traffic was sent out of an unexpected interface after upgrading to ESXi 5.  This particular bug surfaced while troubleshooting my iSCSI bug (because why … [Read more...]

vSphere 5 Networking Bug Affects Software iSCSI

Update 1: This issue was fixed as of 3/15/2012 in ESXi 5.0 Update 1 per the original knowledge base article: VMware KB 2008144. To download ESXi 5.0/vCenter Server 5.0 Update 1, see the VMware Download Center.  Update 2 (Nov 7 2012): While VMware says the issue was fixed in vSphere 5.0 Update 1, I have not found this to be the case.  I've had several environments where the bug was still present, and in some cases this nasty bug still appeared when implementing the Failback = NO setting on the vSwitch.  Additionally, setting Failback = No may cause some other problems - see my update here … [Read more...]

HA Errors after vSphere 4.1 Upgrade

I recently ran into an issue with one of my vSphere clusters after upgrading from vSphere 4.0 to vSphere 4.1 (with ESXi 4.1 and vCenter 4.1).  After the upgrade, I attempted to enable VMware High Availability (HA) on the upgraded cluster.  Each of the ESXi hosts in the cluster appeared to have been properly configured for HA (as observed in the 'Recent Tasks' pane of the vSphere Client).  Despite having appeared to configure HA correctly, I found that each host in the cluster was displaying an error on the Summary tab of the vSphere Client that read 'Error <date> <time> HA agent on … [Read more...]