Hi soso
I have both optical drives on the same (PATA) IDE channel and they are Ultra DMA 2 and Ultra DMA 4. The burner being the latter. This is the onboard motherboard channel.
This is what I get in the log. Note the burn time

Getting media info [E]
Extracting Sector
Security Sector extracted from LBA sector 129823
Checking Stealth Compatibility
Video is questionable*
PFI is present
DMI is present
SS is present
Stealth Check Passed!
Getting media info [E]
Disk Book Type: DVD+R DL
Media Type: DVD+R DL (Blank, Manufactured by MKM)
Bytes Available: 7,96 GB (8 547 991 552 bytes)
Starting write process...
TAG Located
Xbox Version: Xbox 360
Hack Version: 3
Created By: XBC v2.3
Source Drive: DVD-ROM SH-D162C
Mode Parameter = Xbox 360
Checking Stealth Compatibility
Video is questionable*
PFI is present
DMI is present
SS is present
Stealth Check Passed!
Data Sizes:
Total: 7,05 GB (7 572 881 408 bytes)
Creating Buffer: 20,0 MB
Prefilling buffer
Buffer Filled: 100% 20,0 MB (20 971 520 bytes)
Using XBC to write image
Initializing Writer [E]
Opening for exclusive access [E]
Disk Book Type: DVD+R DL
Image size 7,05 GB (7 572 881 408 bytes)
Setting Write Speed to: 2,4x (3 324 KB/s)
Write Speed set to: 2,4x (3 324 KB/s)
Setting layer 0 capacity at: 1913760 sectors
Reserving Track; Sectors: 3697695
Performing Optimum Power Calibration
Syncing Cache
Initialization complete
Starting write
Removing TAG information
Write complete
Syncing Cache
Closing Track
Finalizing Disk
Getting media info [E]
Media Type: DVD+R DL
Bytes Used: Unknown Disk State
Write completed in 05:04:30