I had a small VMWare environment with one host running the free version of vSphere 4.1 for about five guests. The guests were all Windows 2003 servers which I had P2V'd from old hardware. The host is a Dell R900 with 4x500GB disks in RAID10. There was only direct attached storage - no SAN, no iSCSI. I wanted a backup/replication solution to protect business continuity in case of server failure. I wanted an automated way to replicate guests from the primary vSphere host to a second vSphere host (located in the same building but in another room) which could be manually powered up in case of small disaster, like the first host crashing or the room springing a roof leak.
Vizioncore and Veeam offered backup products that would do the job, but would cost thousands of dollars. I noticed the free ghettoVCBg2 script should let you replicate guests from one host to another host. The only requirement would be a vSphere Essentials license which is $495. I wanted Essentials anyway for vCenter server to manage multiple hosts.
I was able to get it working, but not quite the way I had planned. The monkey wrench is that VCB/vMA can't copy VM's running on local storage on one host, to local storage on another host, since the vMA guest needs datapaths to both datastores. So ghettoVCBg2 can't really backup machines between hosts.
The workaround I found was to virtualize the local storage on the second host by running a Virtual Storage Appliance (VSA). The host has 1TB of disk, and the largest VSA I could fit in there was about 920GB, so I'm not losing too much space. I used HP/Lefthand's HP4000 VSA. Free VSA's are also offered by EMC, Falconstor, SvSAN, and soon by NetApp, but I haven't tried those. The VSA presents 900GB of iSCSI storage which both vSphere hosts can connect to. In case of disaster, the local adminsitrator can connect vCenter client to the second host and open the .vmx files stored inside the VSA, and then boot up last night's snapshots.
There's a gigabit link between vsphere01 and vSphere02. ghettoVCBg2 takes about three hours to snapshot 750gb of vmdk from vSphere01 to the VSA on vSphere02, which makes it okay to do every weeknight. Can't run it during the day without slowing down running guests to a crawl. One problem with the HP VSA is that the OVF came prepackaged with a VMXNET2 and not a VMXNET3 NIC, which bottlenecks iSCSI performance even when running locally.
So, my basic setup is two Dell R900's running vSphere 4.1 with Essentials license, a vMA running ghettoVCBg2 by cronjob, and an HP VSA virtual appliance. The environment also has two other physical servers: a Windows AD domain controller plus the vCenter server. It seems to work and provide a small degree of BDR, but I wonder what others recommend for doing it better.