Can you Vmotion between different physical data centers?

Posted on June 15th, 2008 in SAN, esx, replication, vmotion by Rich

Chad Sakac has a great post on his Virtual Geek blog titled The Case For And Against Stretched ESX Clusters. In this post Chad discusses the possibilities of configuring ESX Clusters between 2 different physical data centers. That is, spanning the SAN across a wide area network so that VMs can be vmotioned between sites. The concept is a frequently discussed desire of many administrators, and Chad brings to light some great points for and against this design with specific configuration details about making it work with VMware ESX.

For example, the post explores several options:

Avoid Hot VMware Snapshots When Using Storage Array Snapshots

Posted on June 7th, 2008 in SAN, esx, microsoft, netapp, replication, srm, storage by Rich

Avoiding storage array snapshot pitfalls in a VMware environment is an article and tip published by Scott Lowe for Searchvmware.com. Scott discusses the design challenges and implications of combining the snapshot abilities of VMware ESX with the SAN based snapshot features of storage devices. The tip points out that incorrect configuration of VMware ESX with the storage device could lead to inconsistent and unusable images when trying to recover VMs.

“Because these snapshots are not, by default, integrated in any way with VMware ESX Server, we have to perform a few extra steps to ensure consistently reliable and usable storage array snapshots.”

Read all of Scott’s tip at the link to the article above.

My “2 cents” on this is that trying to configure the combination of the two snapshots manually might not

XenServer integrates everRun VM for HA features

Posted on March 25th, 2008 in XenServer, XenSource, availability, citrix, dr, fail over, feature comparison, replication, vmetc.com, vmworld by Rich

everRun VM diagramCompared to VMware ESX Enterprise Edition, business continuity and high availability features are lacking when deploying Citrix XenServer “out of the box.” Specifically, XenServer does not have the built in equivalent to VI3’s HA feature. Also missing is a solution similar to VMware’s soon to be released Site Recovery Manager (SRM). However, Marathon Technologies and XenSource (now a division of Citrix) have worked together to develop everRun VM as a enterprise class answer to fault tolerant availability for Windows virtual machines hosted on Citrix XenServer. According to Marathon’s Director of Products, Michael Bilancieri, at a recent Atlanta “Virtualization for the Real World” event, the integrated solution will be generally available sometime in the 2008 Q2/Q3 time frame.

Quoting from the Best of VMworld (more on this award later in this post) white paper downloadable from the everRun link above:

Using VMs for physical server disaster recovery

Posted on February 18th, 2008 in P2V, dr, platespin, replication, vizioncore, vmware server, vranger by Rich

One of the advantages of a virtual infrastructure is the ability to cost effectively replicate your production systems to a secondary disaster recovery environment. Not only can you do this with virtual machines, but there are now several options available to allow physical servers to be replicated to a stand-by VM. This post will briefly cover several products and solutions and provide multiple commercial options and a free alternative.

Yes, you will need more than T1 bandwidth for VI replication!

Posted on November 5th, 2007 in SAN, dr, esx, replication, vizioncore, vmware by Rich

Too many companies try to implement replication to a DR VI without upgrading the bandwidth between the primary and secondary sites. Let’s look at a simple example that can illustrate what could go wrong with inadequate bandwidth.


A company has 5 VMs that each use 20 GB virtual disks. The data is not too dynamic and data change only averages about 1o% per business day or roughly 1 GB per hr. This data change could be common activity like Active Directory replication, files saved to user home folders, application databases, and email. This is common to a small to medium sized business.

Using the Data Replication Minimum Bandwidth Requirements chart provided by NSI, makers of Double-Take, You can see that the 100 GB falls into the LAN 10Mb/s bandwidth category (in the 10% column). Click the thumbnail image to the left for a better view of the chart. We’ve already proved that this company needs better than a T1, but it’s close enough not to convince those that think their data change will be lower than 10%.

The real “gotcha” is that companies never consider how long it will take to replicate the data.

Replicate your VMFS partitions - NetApp

Posted on September 13th, 2007 in SAN, netapp, replication, sol exchange, storage, vmworld by Rich

Another “ton of bricks” moment happened to me when I was talking about SAN replication with NetApp yesterday in the Solutions Exchange. Using your WAN, NetApp’s products can replicate block level data between each other, or they can replicate the data from your existing SAN.

So, this means that I can buy a single NetApp product and put it at my DR site and start replicating my VI for fail-over. I don’t even need to worry about building the ESX infrastructure right away. Although, the ability to test my DR fail-over requires I have ESX servers at my secondary site.

I asked for general pricing for a small office SAN. I guestimated about 3TB of data would be needed. Although they wouldn’t give me a firm quote I was told pricing should be somewhere in the $10k - $15K range.