Backup cluster with esxi 5.5 and 6.5

[MinoDC]

Hi to all...
I've an infrastructure cluster VMware with host 5.5 and 6.5
vCenter is 6.5 U3 and veeam 9.5U4b .
Datastore are VMFS 5.

The issue is this...when try to backup vm i receive the error "unable to mount datastore" (before upgrade to 6.5, all worked fine) .
Now if i select failover to NBD, the backup works via network, but via san i can't backup vm.

If disconnect/power-off Host 6.5 all works...
If disconnect/power-off Host 5.5 , but VMFS is 5 not works...
If connect Host 6.5 to a datastore VMFS 6 all works..

I tried to move backup server on host 6.5, but without success.

Can anyone help me ,please ?

Thanks for any suggestions-

[Egor Yakovlev]

Hi Girolamo, feel free to open a support ticket.
It seems that your 6.5 host doesn't like old VMFS5 datastore for whatever reason there might be. Just wondering, is there any particular business reason to keep cluster mixed mode anyway? I mean you will not be able to utilize new 6.5 features on same VMFS5 datastore mounted to 5.5 host, you will not be able to mount new VMFS6 datastores back to 5.5 hosts, you will not be able to utilize newer VM Hardware Version as it will cause 5.5 compatibility problems so on.
/Cheers!

[MinoDC]

I'm sorry...there was an error in my transcription ...

my vmware infrastructure has two cluster (one with esxi 5.5 and one with esxi 6.5) managed from the same vCenter.

The Host 6.5 can manage VM fine, on VMFS5 (then it means that it works fine with VMFS5)

The issue is that veeam, i don't know why, hasn't been making backups since i added 6.5 hosts

[Egor Yakovlev]

Well it might be due to Proxy settings - if it is strictly set to have Direct SAN Access mode(no "Failover to network" selected) and it is not configured for new cluster(LUNs aren't presented), than jobs will fail. And, as you say they will work fine, when switching to Network Mode. Check proxy settings.
/Cheers!