Sizing considerations
This section describes the CDP gateway's sizing requirements, based on your environment's workload.
Note:
Special configuration is needed if you plan to support a large number of VMs using the CDP gateway. Deploy the CDP gateway and the MSDP or media server hosting the storage unit, on different hosts.
Note:
If the CDP gateway and MSDP are co-located on the same media server, then the CDP service consumes 20% of available memory (RAM) for its internal use. If the CDP gateway is standalone on the media server, it consumes 50% of the available memory for the same. From
You need to size the CDP based on the number of VMs that you want to protect. Consider the requirements that are described in this section while calculating the requirements for the gateway.
CDP enables you to continuously tap the I/Os done by the VMs. By default NetBackup uses 10-GB storage space on the staging area per VM. When IO tapping starts, the CDP service starts writing the data into this 10-GB storage. Once this storage limit is reached, the CDP service (nbcctd) initiates a backup job to move this data from the gateway to the backup storage.
Out of the total available space on the CDP staging path, by default NetBackup reserves 25% for usage beyond the allocated storage per VM. This storage is common for the subscribed VMs to the gateway. See the following topic for more information.
See Defining the CDP gateway .
Storage requirement for the gateway
When NetBackup receives the data from the ESXi I/O daemon, it stores the data in the in-memory cache. The recommended value is a minimum of 160 MB of data for each VM.
For example, you can protect 40 VMs in a gateway. So, you need 40*160 MB = 6400-MB RAM. Allocating more RAM increases the in-memory cache size when the CDP service starts, ultimately increasing the I/O performance of the service.
Similarly, to stage 40 * 10-GB = 400-GB (75%) + 134GB (25%) reserved, that is approximately 540-GB space you need to have in the staging area.
Increasing the storage for each VM allows to NetBackup to back up more data per backup job. Increasing the reserved storage for the CDP gateway lets you receive more data without any interruption to the protection. Note that even when the staging path is fully occupied, it does not affect the applications inside the VM. NetBackup catches up the data that the applications produce during that time, and moves it to the backup storage in the subsequent backup jobs.
Note:
If NFS is used for the staging area, the minimum required throughput is 100 MB/sec.
When you start using the CDP feature, it is important to observe the system and tune it according to your business demands. Add any required hardware configurations to maximize protection and performance. First, you can use default values and start subscribing the VMs according to the requirements in this section. You should review the following:
The number of immediate backup jobs that the CDP service initiates due to the staging storage in full condition.
CDP backup engine notifications in the NetBackup web UI.
The performance of the underlying provisioned storage. For example, the NetBackup installation disk, CDP staging area, and MSDP storage disks.
Network utilization and available bandwidth.
CPU and memory consumption when data is received from the ESXi, and when the backup jobs are running.
Note:
If you observe slow I/Os from the I/O daemon, review the network bandwidth and system RAM. See the following topic for how to increase the in-memory cache size.
See Defining the CDP gateway .