Is your improvement request related to a feature? Please describe (👍 if you like this request)

According to preliminary results in #5159, replacing the iSCSI frontend with UBLK has shown significant performance gains. Currently, v2 uses nvmf-tcp as its frontend protocol, but SPDK also supports UBLK (see UBLK documentation). The purpose of this ticket is to further compare nvme-tcp with UBLK to determine if UBLK could replace nvme-tcp, and to explore the associated error handling strategies.

Describe the solution you'd like

• Compare the performance of nvme-tcp and UBLK in various scenarios, focusing on data transfer rates, latency, and resource utilization.
• If UBLK is identified as a potential candidate, investigate the feasibility of replacing nvme-tcp with UBLK as the frontend protocol.
• Develop error handling procedures to ensure stability and reliability when using UBLK.

Describe alternatives you've considered

Retaining the current nvmf-tcp protocol and optimizing its performance.

Additional context

https://spdk.io/doc/ublk.html