Managing VADP backup proxies

In IBM Spectrum Protect Plus, you must create proxies to run VMware backup jobs by using vStorage API for Data Protection (VADP) in Linux environments. The proxies reduce demand on system resources by enabling load sharing and load balancing.

The backup of a VMware virtual machine includes the following files:
  • VMDKs corresponding to all disks. The base backup captures all allocated data, or all data if disks are on NFS datastores. Incremental backups will capture only changed blocks since the last successful backup.
  • Virtual machine templates.
  • VMware files with the following extensions:
    • .vmx
    • .vmfx (if available)
    • .nvram (stores the state of the virtual machine BIOS)

At least one VADP proxy must be enabled in the backup site that is specified in the SLA for VMware backups. For more information, see Creating VADP proxies.

The processing load is shifted off the host system and onto the proxies for VMware backup jobs. When more than one VADP proxy exists, throttling ensures that multiple proxies are optimally utilized to maximize data throughput. For each VMware virtual machine being backed up, IBM Spectrum Protect Plus determines which VADP proxy is the least busy and has the most available memory and free tasks. Free tasks are determined by the number of available CPU cores or by using the Softcap task limit option.

If a proxy server goes down or is otherwise unavailable before the start of the job, the other proxies take over and the job is complete. If a proxy server becomes unavailable when a job is running, the job may fail.

Transport modes describe the method by which a VADP proxy moves data. The transport mode is set as a property of the proxy. Most backup and recovery jobs are later configured to use one or more proxies.

VADP proxies in IBM Spectrum Protect Plus support the following VMware transport modes: SAN, HotAdd, NBDSSL, and NBD.

Although every enterprise differs, and priorities in terms of size, speed, reliability, and complexity vary from environment to environment, the following general guidelines apply to the Transport Mode selection:
  • SAN transport mode is preferred in a direct storage environment because this mode is typically fast and reliable.
  • HotAdd transport mode is preferred if the VADP proxy is virtualized. This mode supports all vSphere storage types.
    Note: To use only the HotAdd transport mode without falling back to alternate transport modes, select VADP proxy uses only HotAdd transport mode in Global Preferences. For more information, see Configuring global preferences.
  • NBD or NBDSSL transport mode (LAN) is the fallback mode because it works in physical, virtual, and mixed environments. However, with this mode, the data transfer speed might be compromised if network connections are slow. NBDSSL mode is similar to NBD mode except that data transferred between the VADP proxy and the ESXi server is encrypted when using NBDSSL.