InMage Brings CDP and Replication to vSphere

Server virtualization has been a blessing and a curse to those of us that worry about data protection and disaster recovery. Virtual servers make equipping the DR (disaster recovery) site easier and a lot less expensive, but traditional backup and replication solutions have been somewhat inadequate for the virtual server environment. InMage's vContinuum brings real-time Continuous Data Protection (CDP) and asynchronous replication to vSphere environments and does it at a very attractive price.

Organizations looking to protect their virtual server infrastructure and provide application recovery at a DR site have had to choose between three basic protection models. Those with deep pockets can use VMware's Site Recovery Manager (SRM). You'll need a pair of disk arrays that can replicate the data and have the SRM driver, which VMware calls an adapter, to enable SRM's application recovery. Array replication can be expensive and requires the arrays at both locations be from the same vendor and product line.

The second option is to use host replication and application recovery software such as NeverFail, Double-Take or WANsync in each of the virtual machines you want to protect. The problem I've long had with host-based replication is that you have to manage each replication pair separately. For example, you can throttle the Exchange server replication to not use more than 1Mbps and the SQL server to not use more than 1.5Mbps, but you don't typically have the ability to set replication traffic to 5Mbps and give SQL server priority over file updates.

Option three is to use one of the VMware-specific backup applications from Veeam, Vizioncore (now Quest Software) or PHD Virtual. While they don't provide automated application recovery (you have to change the server IP addresses to the subnet at the DR site and update DNS for failover), the best of these, like Veeam's Backup and Replication, do let you mount a backup image and bring a VM back without waiting for a restore. The problem is that they're really backup apps, so while you can set Veeam Backup to run an incremental backup every 15 minutes and replicate the changed blocks to a remote site, it's still periodic. In addition, the copying could affect system performance as the backup process and primary server access the same disk at the same time.

What I've wanted is host-based replication that runs in the hypervisor. Then I could manage VMware host replication pairs instead of managing each application server and its doppelganger. Unfortunately, VMware doesn't have any place to get disk updates as they're written, so vendors like Veeam and Vizioncore have to use the changed block backup API after the fact. Enter InMage. Its vContinuum is based on the technology behind InMage's Scout CDP appliances. The company has taken the core of Scout and turned it into a virtual appliance that integrates into vSphere. The vContinuum virtual appliance then installs lightweight agents into the VMs you want to protect. The agents act as write splitters: they duplicate each disk write to the vContinuum virtual machine, which will send it to another vContinuum VM across the local and/or wide area network. Because the write splitter is in the machine being protected, it can exclude junk writes to temporary or swap files that don't need to clog your network.

The target vContinuum VM creates doppelganger VMs for your protected machines and allows you to recover the VM to any point in time. Because the target system is writing to a VMware datastore, you don't need the same kind of storage on the primary and backup systems. When the folks at InMage were briefing me, they answered all my questions with the answers I was looking for. You can seed the replication with external hard drives. They provide not just system but also individual file or item recovery, down to the Exchange email message. And they use Windows VSS and application-specific methods for Oracle and others to create periodic consistency points.

To allow longer term retention without needing infinite disk space, vContinuum will reduce the number of restore points over time so you can recover to any point in the last 48 hours, any hour in the last week and any day at midnight for the last month. Finally, they do their own WAN optimization: like everyone else they compress data, but they also let you set VM priorities and accommodate WAN latency.

InMage's vContinuum is available now for $4,000 per protected vSphere host. That's comparable to the VMware backup players and a lot cheaper than the alternatives if you want an RPO of a few minutes. Of course the proof of the pudding is in the eating, and I hope I can talk InMage into letting me run vContinuum through its paces in the lab sometime soon. In the meantime, check out Network Computing's most recent digital issue for more on using virtualization and the private cloud for disaster recovery.