Network usage with different transport modes -Please comment

[sanket.ksinghal]

Hi there,

I am trying to analyze the network usage when Veeam is backing up data using the different transport modes. I want to find out which network segment is the traffic going over during the backup window.

We have split the network in Management VLAN, VLAN for iSCSI, and multiple VLANs for VM traffic.

Question:

1. If the transport mode is Hot Add then will the traffic ride over the iSCSI network / Mgmnt network/ VM Network - This is not very clear while viewing the vSphere performance charts.

2. If the transport mode is nbd - Which VLAN will the traffic go over?

3. For SAN mode - Which network?

4. If a VM is on local storage will it be backed up only on nbd mode?

We are trying to add newer switches to improve backup speed so want to figure out where to start - but having a very hard time trying to pin down the bottleneck

[foggy]

Sanket, I suggest reviewing our sticky FAQ topic section regarding transport modes first, should answer most of your questions. If after that you still need further clarification, feel free to ask. Thanks.

[yizhar]

Hi.

1. If the transport mode is Hot Add then will the traffic ride over the iSCSI network / Mgmnt network/ VM Network - This is not very clear while viewing the vSphere performance charts.

Using Hotadd traffic goes:
Source to proxy traffic = from iscsi storage to esxi host via ISCSI network (Veeam proxy reading source vmdk).
Proxy to repository traffic = Veeam proxy VM to Veeam repository agent via MGMT network or whatever connection between them. This traffic is less busy because it is after dedup and compression, but still should be noticeable.

2. If the transport mode is nbd - Which VLAN will the traffic go over?

Using NBD:
Source to proxy traffic = passes 2 networks. From SAN to esxi via ISCSI network, and also from esxi to Veeam proxy via MGMT network.
From there - if the Veeam proxy is also the repository server, no network traffic while writing to target disk.

3. For SAN mode - Which network?

Source to proxy traffic = From SAN to Veeam proxy directly via ISCSI network.
From there - if the Veeam proxy is also the repository server, no network traffic while writing to target disk.

As you can see above, the main advantages of direct SAN mode are:
* short and fast network path from storage directly to Veeam proxy.
* but the main advantage - the esxi host isn't involved and not part of data path. The esxi host is free to use resources (cpu, ram, iscsi nic, mgmt. nic) for other production tasks, even while the backup is running.

4. If a VM is on local storage will it be backed up only on nbd mode

If Veeam proxy is running on a physical machine then yes, only NBD.
If you configure a Veeam proxy on a VM on the same esxi host, then that Veeam proxy can have direct access to the source VMDK disk using HotAdd mode.

Yizhar