VRA Memory Considerations (ZVR 3.1 and Greater)

KB Number:

When installing a VRA via the Zerto GUI, an administrator needs to select a value for the VRA's memory.  Prior to ZVR 3.1, this value reflected the number of volumes a VRA could support.  Starting with ZVR 3.1, this value is a buffer for IOs.  This article elaborates on the nature of these buffers and the buffer pool sizes associated with the different VRA memory options.


The amount of memory to allocate to the VRA. The amount determines the maximum buffer size for buffering IOs written by the protected virtual machines by the protecting VRA, before they are sent over the network to the recovery VRA. The recovery VRA also buffers the incoming IOs until they are written to the journal.


The VRA memory values and associated VRA Buffer Pool Sizes are as follows:

  • 1GB VRA memory = 461MB VRA Buffer Pool Size

  • 2GB VRA memory = 1485MB VRA Buffer Pool Size

  • 3GB VRA memory = 2509MB VRA Buffer Pool Size


The protecting VRA can use 90% of the buffer for IOs to send over the network and the recovery VRA can use 75% of the buffer. That is, for example, a protecting VRA defined with 2GB of RAM can buffer approximately 1337MB before the buffer is full and a Bitmap Sync will occur.

Affected Versions:
ZVR 3.1 and Greater

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