ESX 4 Fault Tolerance
In the next step in virtualization evolution; VMware is introducing vLockStep. This technology is the beginning of a true active, near zero downtime clusters. David Davis reports on techtarget, that vLockStep will create a standby running image of the VM. This VM is running in step with the primary VM, any change on the primary VM is nearly instantaneously completed on the standby image. In case of hardware failure of the ESX node hosting the primary image, the standby will become active and continue on servicing clients as if nothing happened. A video on VMware’s website demonstrates this active/standby connection very effectively.
There are some additional requirements that Scott Lowe wrote about in his blog at ScottLowe.com. One of the biggest is that the FT pair must use thick provisioned vmdks. Then provisioned disks will be expanded to thick. On an NFS based datastore, one of the benefits is to leverage thin provisioning. Scott also writes that a minimum of 4 NICS are required to support vLockStep: Service Console, Clients, FT, and vMotion. Given that redundancy is a given in the production environment, we are now up to a minimum of 8 nics, and at least 2 more if the NFS datastore is used.
Also, there are limitations to vLockStep. One such limitation is that the VM guest can only be single vCPU. A second limitation is that the secondary VM must reside on the same datastore as the primary. I’m making an assumption on the third limitation: It would appear that the secondary VM will need to run on the same VI cluster as the primary.
The first limitation of single vCPU is the largest shortcoming of vLockStep. Most of the critical applications that would benefit from a truly active cluster are going to be database servers and mail servers. Critical servers that the entire business requires, most of these servers are going to be multi vCPU. The second and third limitation would have been niceties. Placing a vLockStep enabled VM across both multiple datastores and multiple clusters would have truly enhanced the disaster recovery capabilities of VMware. Firms would be able to survive not only a small ESX host failure, but also entire storage failures, Power Failures, natural disasters. Hopefully, the vLockStep technology will be enhanced in future releases of ESX.
David Davis discussing vLockStep Technology: http://searchvmware.techtarget.com/video/0,297151,sid179_gci1336986,00.html?track=NL-915&ad=670476&asrc=EM_NLN_4862015&uid=2353064
VMware Site demonstrating vLockStep Technology: http://download3.vmware.com/vdcos/demos/FT_Demo_800×600.html
Scott Lowe’s Blog on vLockStep: http://blog.scottlowe.org/2008/09/16/bc2621-fault-tolerant-vms-in-vi-operations-and-best-practices/
Black Friday for Us
I woke my wife up at 3AM to the sounds of Reveille blaring from my iPhone. While she was not enthused with my choice of music, she was less enthused with waking up at 3AM. I told her the mission calls for it. While we haven’t been impacted significantly by the economic downturn, we have reduced our discretionary spending to make up for the rise in costs of gas and groceries. So, our mission was to do knock the holiday shopping out for as little as we could; and that meant getting up at 3AM to participate in the carnage that is “Black Friday.”
We were able to get most of what we were looking for. One item we wanted to purchase at Walmart, was the Leapster. This is for my three year old, we were standing next to the roughly 4X4X4 foot box at 4AM. The sale did not start until 5AM. So for an hour, I listened to Metallica and the like, building up the rage. At 5 AM, when the Walmart employee opened the box, what I experienced was as violent as a mosh pit. There was a surge from the front trying to get through the front line; only to have about 30 or so of the Leapsters. Under this massive box, they had 4 display cases of Leapsters. Looking at the size of the shipping box, we were expecting at least twice that. I thought I wasn’t able to get one as I was in the second row. Luckily, one of the ladies in the front row, grabbed two and since I had been standing there for that long. She offered me one. Now I’ll have an excited three year old.
We still have a little shopping to do, but we are mostly complete. And we were able to do it without going heavily into debt.
About mordtech
Experience:
I’m an IT professional with over ten years of Microsoft Server support. I’ve also supported Checkpoint and VMware. I’m currently employed by a large IT outsourcing corporation in the US.
I’ve implemented Windows Active Directory, Checkpoint VPN/Firewalls, VMware Infrastructure, Sharepoint/Project Server amongst others.
Personal:
I’m married and a father of two boys, which is by far the most trying job of my life: the boys, not the marriage. We reside in the midwest and aren’t looking forward to the fast approaching winter.
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