MAX NFC connection buffers for network backup

[mbafna]

Hi,

VDDK documentation suggests  "sum of all NFC connection buffers to an ESXi host cannot exceed 32MB".  Every while and then we see NBD_ERR_INSUFFICIENT_RESOURCES error coming while backup is running sometimes even with less no of VM backups running.

I am running into some queries due to this -

Can we verify this value on ESXi server?

Can we verify how much is in-use while backup job is running?

Can this be increased from ESXi server?

How can we find answers why we might be seeing NBD_ERR_INSUFFICIENT_RESOURCES and ways to avoid it?

Appreciate your responses!!

Thanks!!

[Finikiez]

Hello!

Check this KB article VMware Knowledge Base

[mbafna]

Thank you for response!

"esxcfg-advcfg -s 32768 /BufferCache/MaxCapacity" is not ESXi NBD buffer. rite?  If it is then is NBD buffer by default 16MB? All VDDK documentation seems to suggest it can be MAX 32MB per host and doesn't mention about this tune!

[Finikiez]

I think that this is a buffet which you are looking for.

What is a value you have on your ESXi host? What is your ESXi version?

And what is your backup software and version?

[mbafna]

Thanks for reply.

I have checked on ESX 6.0 and ESX6.5, ESX 6.7. I see all of those show 16MB as default value for - "/BufferCache/MaxCapacity"

# esxcfg-advcfg -g /BufferCache/MaxCapacity

Value of MaxCapacity is 16384

# uname -r

6.7.0

Now since VDDK documentation doesn't talk about "/BufferCache/MaxCapacity" and also it says 32MB max (but doesn't say anything about default). This leaves confused what is default NBD buffer size?