System Requirements for Live Sync I/O with VMware

This topic summarizes requirements for Live Sync I/O.

To avoid delays in replication, implement the following best practices:

  • Use a low latency network.
  • Provide enough cache space and a fast storage connection to the cache on the VSA proxy at the source site.
  • Provide a fast storage connection to the RP Store.
  • Provide enough storage for the RP Store.
  • Timestamps must be synchronized between VSA proxies and ESXi hosts.

Hypervisor Support

vCenter and ESXi Requirements

  • vCenter Server version: 6.5 or 6.7
  • ESXi memory requirement for each VM: 100MB
  • On the ESX cluster, vSphere High Availability (vSphere HA) must be configured and vSphere Distributed Resource Scheduler (DRS) must be enabled.


  • Two VSA Proxies: One at the source site and one at the destination site.
  • MediaAgent should be present on the destination proxy.
  • Low latency network between the proxies, preferably 10 Gigabit Ethernet, depending upon I/O loads.
  • The destination requires a fast storage connection to the Recovery Point Store (RP Store).

Virtual Machine Disks

Before configuring a source VM for Live Sync I/O, ensure that the VM storage policy in vSphere is set to Datastore Default for all disks.

Proxy Computer Operating Systems

  • Microsoft Windows Server 2016
  • Microsoft Windows Server 2012 R2 x64 Editions
  • Microsoft Windows Server 2012 x64 Editions
  • Microsoft Windows Server 2008 R2 x64 Editions

Note: Linux proxies are not supported.

Plug-In Installation or Upgrade Requirements

VMware vCenter Server Privileges

  • Ensure that vCenter permissions are configured correctly as described in Permissions for Custom User Accounts.
  • The VMware vCenter Server user account used to install plug-ins must have administrator privileges for installation or upgrade.

Acceptance Level

  • For each ESX host, the acceptance level can be any of the following:
    • VMwareAccepted
    • PartnerSupported
    • CommunitySupported

Licenses and Features Enabled

  • During installation or upgrade of the Commvault plug-in, ESX servers go into maintenance mode, which requires that vSphere High Availability (vSphere HA) is configured and vSphere Distributed Resource Scheduler (DRS) is enabled.
  • Plug-ins must be part of protected and replicated data centers (ESX clusters).

Source Proxy Cache Requirement

  • Cache location: Job Results directory
  • To increase the cache size for each VM being replicated, you can configure the BLR\nMaxCacheSizeMB additional setting on the VSA proxy at the source site. If the cache size is not sufficient to handle the expected I/O, including I/O spikes and considering network speed, throughput, and latency on writes at the destination site, you might experience delays in replication or, in the worst case, a loss of recovery points.










    32 GB for each VM (default)

    For instructions on adding additional settings from the CommCell Console, see Adding or Modifying an Additional Setting.

  • To change the cache directory, you can configure the BLR\sCacheDir additional setting on the VSA proxy at the source site.










    cache_directory_path (by default, <ContentStore_path>\iDataAgent\JobResults\BLR)

Network Bandwidth

Provide network bandwidth based on the estimated I/O speed. For example:

  • Protected VMs: 10
  • Rate at which each VM performs I/O: 100 MB/s
  • Preferred Network Speed: 1000 MB/s

Preferred Recovery Point Store (RP Store) Requirement

Size the RP Store based on I/O throughput and RP Retention criteria. For example:

  • RP Store I/O throughput: 100 MB/s
  • Total Retention Time (hours): 5 Hrs
  • RP Store size: 1800000 MB (1.72 TB)

Note: By default, the maximum size of the RP Store is 500 GB. You can change this limit by editing the RP Store properties. When the content in the RP Store reaches the maximum size, the BlrSvc starts pruning recovery points for the replicated VM.

Firewall Port Requirements

For environments that include a firewall, open the following ports:

  • For ESXi servers on the source site, open port 38403.
  • For ESXi servers on the destination site, open port 38404.

These ports are used by the BLR service to communicate with VAIO daemons.

Last modified: 11/15/2019 10:48:32 PM