Archive for the ‘vSphere’ Category:
How to Add VMware Paravirtual SCSI (PVSCSI) adapters.
A few months before the vSphere release VMware showed some amazing stats in regards to the increased level of I/O that can be attained in a virtual infrastructure. They posted this info on their blog and the outcome of the testing was impressive. They were able to achieve 350,000 I/O operations per second on a single vSphere host (ESX 4.0) and with just 3 virtual machines. Their testing utilized the EMC Enterprise Flash Drives, which have an incredibly high throughput. They talked about how the VMware Paravirtual SCSI (PVSCSI) adapter was able to achieve 12% more throughput with 18% less CPU cost compared to the LSI virtual adapter.
Those stats are equally impressive, since being able to achieve an almost 20% CPU decrease while increasing performance means more density per virtual host. This further allows companies to squeeze more resources from their virtual infrastructure without needing to purchase more hardware. And in this economy, everyone is trying to get their money’s worth when it comes to their infrastructure capital spending.
VMware Fault Tolerance
vSphere was just released to general availability today, and one of the best features of this upgrade is the addition of VMware Fault Tolerance. From the VMware site:
VMware Fault Tolerance is leading edge technology that provides continuous availability for applications in the event of server failures, by creating a live shadow instance of a virtual machine that is in virtual lockstep with the primary instance. By allowing instantaneous failover between the two instances in the event of hardware failure, VMware Fault Tolerance eliminates even the smallest of data loss or disruption.
At VMworld 2008 they let us play with a demo of VMware FT, and it really is an amazing technology. Almost like watching your first VMotion (“You mean the VM moved from this server to that server?”). VMware FT will allow you to have two running versions of the same virtual machine. If you lose a host, the VM will continue running with no dataloss and minimal downtime (technically just a couple pings drop, but your users would not be likely to notice a disruption of service). VMware FT does this by sending the same CPU instructions to both CPU’s via a FT logging NIC, which is a dedicated gigabit or better ethernet NIC on your vSphere hosts.
With any software that gives you that kind of power, there are some caveats and requirements to make FT work in your environment. I felt it was a good idea to start a blog post that I could update with the various requirements for the use of FT with vSphere. This list is my no means all-inclusive, but simply a place where I can keep track of the needs and caveats of FT. Read more for my listing of requirements that I’ve found thus far.