We recently patched our Linux estate - Master, and Media Servers - kernel, and packages.
We back up our File Persona shares via Samba mounts on the Media Servers to StoreOnce. Media Servers are running RHEL 7, and NBU 8.1.1.
Since the patching, all Smba backups are at best 300Kb per second.
We downgraded Samba which worked for 1 backup, but went back to very slow again. So we downgraded the kernel to what it was. Same again, quick for 1 backup, but then very slow again.
So we have disabled some Spectre and Meltdown mitigations which inityially helped again when we tested 1 backup, but everything back to very slow again.
Has anyone got any ideas, or even seen this behaviour. We have an open ticket with RedHat. Spoke to Veritas support, but as Samba is OS package, they cannot help.
from the random outfield...
...it's not clear to me which machine is the "client" in your setup, but if you use the client property "buffer_size", try removing that property - I am not talking about "net_buffer_sz" nor am I talking about any of the typical tuning buffer settings - I am specifically talking only about the one single client property named "buffer_size".
Can you manually transfer some files outside NBU ... just to 100% remove NBU from being involved ...
(It probably isn't, but just in case everything transferrs 100% speed 'outside' NBU we had better check)