We had a discussion internally around memory limits and what the use case would be for using them. I got some great feedback on my reply and comments so I decided to turn the whole thing into a blog article. A comment made by one of our developers, which I highly respect, is what triggered my reply. Please note that [...]

Today I received a question around the difference between IOPS and CMDS/s. The reason for this was the high value of CMDS/s in “esxtop” which exceeded the expected amount of IOPS the disks could actually digest. I thought it would useful for everyone to know what the difference is: IOPS = Input/Output Operations Per Second Within esxtop this would be [...]

Not sure why hardly anyone picked up on this cool youtube movie about Storage IO Control(SIOC), but I figured it was worth posting. SIOC is probably one of the coolest version coming to a vSphere version in the near future. Scott Drummonds wrote a cool article about it which shows the strength of SIOC when it comes to fairness. One [...]

By now the whole world has probably read that vSphere 4 Update 2 has been released. (release notes vCenter, release notes ESX, release notes ESXi ) Some of you might have even started slowly upgrading their test systems. (Like I am doing at the moment…) I will not copy the full release notes but I do want to point out a [...]

On twitter @heiner_hardt asked for help with a performance related issue he was experiencing. As I am starting to appreciate esxtop more every single day and I really start to appreciate solving performance problems I decided to dive in to it. After the initial couple of questions Heiner posted a screenshot: Heiner highlighted (red outline) a couple of metrics which [...]

Yesterday we had an internal discussion about the support of PVSCSI in combination with a 64bit OS. VMware’s documentation currently states the following: Paravirtual SCSI adapters are supported on the following guest operating systems: Windows Server 2008 Windows Server 2003 Red Hat Enterprise Linux (RHEL) 5 source As we normally spell out every single detail this KB article is kind [...]

I received a couple of questions around my esxtop article yesterday so I guess it wasn’t completely clear what “locked” meant. I had a difficult time understanding it myself but I was fortunate enough that one of my colleagues (Thanks Valentin) got to the bottom of it and emailed me the following explanation. I rewrote parts of it and this [...]