Does virtio blk support traffic flow during hot-plugging？

[HAOkwills]

Comparison of Windows driver logs for cloud host block device hot-plugging with and without traffic flow.

Without traffic flow during hot-plugging – The disk can be successfully removed. At the driver layer, a PNP removal request is received and successfully processed.

With traffic flow during hot-plugging – During FIO flow testing, when executing the gs command to remove the disk, the driver layer does not receive a PNP surprise removal (hot removal) request. After the flow testing ends, no PNP removal request is received either.

Subsequent gs removal command (without traffic flow) – Only after issuing the gs disk removal command again (without traffic flow) does the driver layer receive a PNP removal request, which is then successfully processed.

[HAOkwills]

Does virtio blk support traffic flow during hot-plugging？Why it cannot deal with this issue?

[kostyanf14]

@HAOkwills currently, we do not officially support the hot-plugging/hot-unplugging flow. If it works - good, if does not - not supported.

[HAOkwills]

Thank you for your response. I would like to ask, in which part of the code might there be potential issues preventing support for hot-plugging with traffic flow? Additionally, when and which component, code sends the PNP surprise removal message to the virtio storage driver?

[kostyanf14]

Theoretically, "PNP surprise removal" can occur when you remove the drive from QEMU on the fly.

[HAOkwills]

Hello, I have one more question. Regarding my code, hot-plugging should correspond to bit 17. However, during the initialization of the QuerySupported function configuration, this bit position was not set—only the first five bits were configured. Could this be the reason?

[kostyanf14]

Yes, this could be a reason.