hotadd async I/O unsupported, WHY?

[zaqik]

Hello!

I look through logs, and see this text

Code: Select all

transport mode: [hotadd], max sectors to read/write: [8192], async I/O: [unsupported]

Why could possibly async I/O be unsupported for hotadd? I've changed VBR VM (it's a Default Proxy) SCSI Controller type to VMware Paravirtual and it didn't help and sincerely I'm out of options to guess. Can you suggest me a direction to dig?

[Sturniolo]

HI there.. welcome to the forums...

That log entry isn't tied to the proxy VM's SCSI controller type, which is why switching to PVSCSI didn't change anything.

Based on the VMware/Broadcom VDDK documentation, asynchronous I/O support is associated with the NBD/NBDSSL transport modes rather than HotAdd transport. Since your job is running in transport mode: [hotadd], seeing async I/O: [unsupported] appears to be expected behavior and not an indication of a failure.

If backups are completing normally and performance is acceptable, this alone usually is not something to worry about. If you're troubleshooting an actual performance issue, then opening a support case would make sense so the data mover logs can be reviewed in detail.

[Andreas Neufert]

If this is a message from the VDDK kit, then remember that we do NOT use VDDK for the actual data transport, we just use it to initialize the processing, then our data mover goes directly to the data to read asyncronously.