VMware vSphere Replication

Data protection is an essential part of business continuity and disaster recovery, and that includes protection of virtual machines. VMware vSphere Replication is an extension to VMware vCenter Server that provides hypervisor-based virtual machine replication and recovery. After initial copy and synchronization of the virtual machines between primary and recovery sites, vSphere continually tracks the changed disk areas, replicating only the data that has changed. The vSphere Replication software can be configured for replication intervals on the VM’s Recovery Point Objective (RPO). 

How Silver Peak helps

When VM data is sent over a Wide Area Network (WAN) and replication sites are separated by longer geographic distances, several factors can impact throughput:

• Distance (latency) can significantly decrease replication performance. The farther the distance between primary and recovery sites, the more time it takes for the recovery site to respond to the primary site during replication. Silver Peak accelerates replication traffic and efficiently using all of the available bandwidth.
• WAN quality (packet loss) can also affect replication performance. Many vSphere Replication customers use Internet VPN connections that typically exhibit packet loss between 1 to 5%.  Dropped packets must be retransmitted, slowing down replication time. Silver Peak repairs dropped and out of order packets in real-time, improving transmission over the WAN.
• Bandwidth is also a factor for replication throughput -- if there is more data to replicate in a given period of time and bandwidth isn’t sufficient, the RPO will be missed. Silver Peak compresses vSphere replication data to minimize the total amount of traffic required to traverse the network. So you can avoid costly WAN bandwidth upgrades.
• Shared WANs can degrade application performance. Silver Peak’s advanced QoS and traffic shaping techniques protect application performance and can reduce the costs by sharing one WAN between vSphere Replicator and other applications.

VMware and Silver Peak

• VMware and Silver Peak Technology Partnership
• VMware vSphere Replication information (on vmware.com)

vSphere Replication Performance with Silver Peak

Testing with VMware vSphere Replication reveals that Silver Peak offers significant improvement for vSphere Replication on WAN links exhibiting packet loss and round trip latency between source and backup sites of 40ms and higher. Below is a snapshot of how Silver Peak software optimized the initial synchronization of Windows 7 virtual machines with vSphere Replicator over a 155 Mbps WAN. Initial synchronization happens when vSphere replication is first enabled on a virtual machine.

Figure 1. Initial synchronization throughput on 155 Mbps WAN (1% loss), at varying latencies

Figure 2. Incremental synchronization throughput on 155 Mbps WAN (1% loss), at varying latencies

Environment:

• WAN speed: 155 Mbps
• 80ms latency
• 1% packet loss

How Silver Peak can help

Silver Peak replication acceleration software is made for storage replication. Deployment takes less than 20 minutes and requires no networking expertise or assistance. Silver Peak overcomes distance limitations between source and target sites by accelerating replication traffic and efficiently using all of the available bandwidth. Silver Peak also protects accelerated traffic with real-time AES encryption without impacting performance.