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hotadd transport for isolated media server

Level 3

I have read through the admin guides and forums and cant find a documented clear solution, I think through practise I know the answer however.

I have a virtual media server (v7.5.0.6) which is isolated in a firewalled subnet with access only to vCenter on 443 and the Master server (1556, 32768). There is no access directly to ESXi hosts (e.g. TCP902).

What I see is, the vCenter snapshot create/delete works fine, however the backup of the snapshot fails due to the transport method not being able to access the snapshot.

The policy is VMware_v2 using hotadd only

Does the hotadd transport draw data off the ESXi host via TCP902?


Partner    VIP    Certified

yes, you are crrect.. you need to have the communication with the port 902

below the below blog


Hot-add Transport

  You can think of hot-add transport as a special case of SAN transport where the backup host is also a virtual machine. Plus there is a bonus, it works for non-SAN data stores as well. The backup host VM accesses the VMDK objects of other VMs directly from the data store (similar to SAN transport). It can protect all VMs on datastores to which it has access.


  No need for a physical backup host

  Does provide offhost backups for those VMs not collocated with VM backup host

  The most efficient backup method for NFS based data stores (e.g. NetApp or FileStore providing VM storage)


  It does use ESX server resources where the VM backup host is deployed

  You cannot protect VMDK files larger than 1TB (a vADP limitation with hot-add)

Level 3

Switch from Hot-add to NBD. I have never seen Hot-add work in all the environments that I have worked with. NBD has worked great. :)

Level 4

To configure Hot-add , Production Esx host should have access on media server storage.

This can be configure through SAN configuration.


I'm using Hot-add , which is much faster than NBD ....

NBD is working on ethernet , and hot-add on fiber ....

Level 4

Is your Virtual Media server on an ESXi host that has access to the datastore on which the VM you are trying to backup resides ?  From what i understand Hot-Add does not go over the network because the snapshot is mounted directly on the backup server.  This will not be possible if the media server is on an ESXi host that cannot see the datastore being backed up. 


With regards to Neeraj's comment, Hot-Add does not necessarily mean that there is SAN in the back-end.  It also works on NFS datastores and local datastores (which is how i have it configured).






Level 3

"Production Esx host should have access on media server storage"

I dont understand what you mean by this?


"From what i understand Hot-Add does not go over the network because the snapshot is mounted directly on the backup server."

I did not realise this, would this work if the hot-add was on NFS and the backup client was on FC Datatstore? (I hope that it would not as we are about to start migrating to NFS.)


There are 5 hosts which all share a common set of Datastores (All vms including netbackup media servers and vCenter are on these datastores). The Media Server in question has no access to the ESXi hosts via vmk IP. It only has access on TCP443 to vCenter vm guest IP (hence snapshot part of backup works).

I have tried another hot-add media server which has access to both vCenter vm IP and all ESXi hosts management IPs and that works fine. (This is what makes me think my hot-add media server needs access to the ESXi hosts managment IPs.

I am backing up to a DataDomain OST device across Ethernet.

This is a strange setup as the vm environment is a single vm cluster with several vm hosts and datastores, however the IP subnetting/VLANs have been divided into three firewalled zones within the single vm cluster.


Level 4

What i was trying to say is that when you do hot-add, regardless of type of datastore (SAN, NFS, local), as long as the ESXi host that your media server sits on has access to those datastores, it should mount the snapshot directly onto your media server.  At that point the data should not have to go through the vmkernel port as it is SCSI mounted like a local disk on your media server.


If you are using NBD transport, that is a different story as the snapshot is being read directly from the ESXi host and transferred over port 902 on the vmkernel port to your media server.