vSphere Replication

[pan1268]

Hello Experts,

I am new to setting up the vSphere replication for standalone hosts in our environment. We have chosen this solution to save costs as this appliance comes with Enterprise plus license. Actually, I have read in one of the community discussion that we need to ensure 3 times more storage at the destination site compared to source site ( or host ) meaning if the my VM total disk size is 100 GB at source host then I need to keep 300 GB of disks at the destination host. Seems first 100 GB is required for the VM itself; another 100 GB is required for the redo file and another 100 GB is required for the SRM automation. Could you please help me to  understand is this a best practice or it is mandatory to have 1:3 mapping before setting up the vSphere replication. Also, if you could guide me to some technical reference which deep dives into the vSphere replication.

Many thanks in advance.

Cheers

[rajen450m]

Hi,

Find the below article which explains in detail and it is not really needed to be 1:3, it all depends on your RPO configuration.

vSphere Replication Target Storage Consumption - VMware vSphere Blog

When replication is first configured, vSphere Replication performs a full sync – it sends all of the data that makes up the virtual machine to the target location to create the base disk of the replica. After the initial full sync, only changed data is replicated – this process is typically called a delta sync. While a delta sync is in progress, the replicated data is stored in one or more redo logs at the target location. Redo logs are used to preserve the integrity of the replica. Once replication is complete, a new redo log is created for the next replication cycle. The old redo log is consolidated into the base disk (or in some cases, another redo log if multiple point in time recovery is enabled – more on that shortly).

Naturally, these redo logs consume storage capacity. How much capacity depends on how much data is replicated and how often replication occurs. A lower RPO means more frequent replication. For example, a virtual machine disk with 100GB of data and a daily data change rate of 6% means 6GB of data would be replicated each day. If replication occurs only once per day (24-hour RPO), the redo log would grow to 6GB as replication is occurring. If the data change rate is consistent throughout the day and replication occurs six times per day (4-hour RPO), the redo log would grow to approximately 1GB each time replication occurs.

Regards,