Archive for the ‘Virtualization’ 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.
Invalid arguments: Virtual machine has no snapshots
I ran into an very interesting issue today with a client who is using Veeam Backup and Replication to keep their virtual machines replicated to a remote ESX server for disaster recovery. Veeam starts a replication job and will take a snapshot of the virtual machine and then replicate the main VMDK disk file to the remote site. When the backup job finishes Veeam will tell VMware to remove the snapshot until the next replication schedule runs. Since we are replicating our VM’s across a slow WAN connection (600Kbps optimized with Citrix WANScalers) the replication can often timeout, or hang. Today I noticed that the replication had not updated since last night. So I needed to stop the replication and re-start it. Since the Citrix WANScalers can cache as well as compress, restarting a failed replication job is usually pretty quick, as most of the data was previously cached on the Citrix boxes.
Here are the details of what I found, and how I fixed it…
How to Extend Windows Boot Volumes in VMware
I am frequently asked the question about how to grow a VMware virtual disk (VMDK) and have it be recognized by the operating system. If you are trying to simply extend a non-system volume within Windows (ie, anything other than the C:\ drive), then the process is pretty simple (refer to MS KB 325590). But when you are trying to grow a C:\ with windows, you need to get around the limitation of extending the system partition. This is just one more instance where VMware shows how powerful and flexible it truly is.
Disclaimer – Before doing anything like this, make sure you have adequate backups and understand that this is probably not supported by Microsoft or VMware – I take no responsibility for any damage to your systems
If you would like to grow a virtual disk the “safe” way (read: much, much slower), you can use VMware’s Converter tool, which will grow the volume for you on conversion, the downside is that it will require the VM to be shutdown during the conversion. The steps below can significantly speed up the process, especially if you have a very large VMDK which needs to be extended.
ESX 3.5 Update 4 Released
I just saw today that it looks like VMware ESX 3.5 Update 4 was released a couple of days ago. I’m pretty excited about this upgrade as it includes an updated vmxnet adapter. From the VMware site:
Expanded Support for Enhanced vmxnet Adapter — This version of ESX Server includes an updated version of the VMXNET driver (VMXNET enhanced) for the following guest operating systems:
- Microsoft Windows Server 2003, Standard Edition (32-bit)
- Microsoft Windows Server 2003, Standard Edition (64-bit)
- Microsoft Windows Server 2003, Web Edition
- Microsoft Windows Small Business Server 2003
- Microsoft Windows XP Professional (32-bit)
The reason this is such a great update, is because of the support for jumbo frames within this new group of OS’s. Previously the enhanced vmxnet driver was only supported on Windows Enterprise and Datacenter versions. When using certain iSCSI arrays which support application consistant data snapshots, you need to install the iSCSI initiator within the virtual machine. This is the only way for the EqualLogic toolkit to take application level snapshots of Microsoft SQL or Exchange Server. Additionally you will require a NIC which supports jumbo frames. Previously this was done via a dirty (and unsupported) hack if you were running the non-supported OS. Now that VMware supports (for data traffic only) jumbo frames for the standard version of Windows OS’s, this can decrease the CPU usage for the guest VM, while not having to spend 4x as much for the enterprise version of the OS. So it’s still “technically” not supported for iSCSI traffic, but works great and can lower the guest CPU usage during high data IO operations.
Additionally, as a old school linux guy and Ubuntu fan, I’m glad they are adding support for newest version of Ubuntu desktop and server, 8.10 – Intrepid Ibex