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vCenter error:

Level 4

Hi Guys,

Has anybody seen this error in vCenter:

My backups fail with....

transport mode: nbd Status 23
Error bpbrm (pid=11183) from client ERR - Error opening the snapshot disks using given transport mode: nbd Status 23

 I am sure that my media server can talk to the esx host on port 902 since some of the guest machines in the same esx host are backing up without any issue. Just a couple of servers having error 23 and the above message from vCenter.

Thanks again for your inputs.


Level 6

Verify name resolution per this technote


Thanks for the feedback.

Saw this technote and made sure that about using FQDNs in the host entries. Backup failures are just on a couple of VMs on the esx host which makes me think there is something wrong with the snapshots on the vmware side.

The error is just very vague.

Partner    VIP    Accredited
What is the transport mode are you using? If are you using nbd these ports, 443 and 902 needs to be open.

So take a look this TN. Its have an excellent explanation about VMware communication on differents transport modes



Yes, we are using nbd and ports 443 to vCenter and 902 to the esx hosts are open.

The 2 servers we were having issues had a successful backups last night without us making any change on the NetBackup side. 

Thanks for the article, I'm sure it's a good read.

Partner    VIP    Accredited


Yes it is..@AbdulRasheed made some TN like that explainimg how to worl vmware backups.



Hi Thiago and All,

I'm really not sure if I shuold be opening a new thread for this, so I prefer to reply in your entry on this post.

I am facing a very similar issue, but maybe mine only shares the sympthoms with this one. Error code 23, transport mode nbd... Ports, routing, name resolution are OK. Credentials used by NBU on VMware side are OK as well ("Administrator", actually). 

I swa something a bit weird though, which is that the NBU Media servier I intend to use as VMware Backup Host does not appear in the list of VMware Backup Hosts inside the Master Server's properties (Java Admin Console). When I try to add it there, I receive an error which says the server I'm trying to add is already in that list.. But I can't see it! Why? Could this be there's some kind of inconsistency within NBU that is causing this issue?

BTW, This is NBU 8.1 (not 8.1.1 yet.)

Thanks in advance. :)

Partially replying to myself,

I managed to add the Media server I wanted to the list of VMware Access Hosts in the Master server's properties using the GUI. It was a lucky coincidence, but there happened to be one host that had to be removed from that list, and that action seemed to unlock mine, which was to add the one I wanted. So, in that sense, configuration is now fine. By the way, I then restarted the whole NBU domain (actually rather small: only two Media servers there.)

However, my main issue is still there: The VMware backup host cannot read the VM snapshot. I'm still troubleshooting. It's getting more likely that I will open a case sith Support...


   VIP    Certified

hello @spider328  -  It seems your vcenter datastore is low on free space. Take a look. Ensure Datastore free space is 2x the size of the VM you are trying to backup. Thanks



You also need to check the account's permissions.

Don't hesitate to enable vxms & bpbkar logs on the vm backup host.

Good luck !