T61 Ultra DMA Mode 2

My T61's ( T7300, 5400 80G HD) HD is runing on Ultra DMA Mode 2. Why? I thought it should be Ultra Mode 5 or higher. What's yours? anybody knows how to fix it? thanks.

 

First, your drive is SATA - they do not use DMA Mode at all - it is an ATAPI specification. SATA uses "transfer rates" - 150 or 300 mbps when addressing memory. Your CD/DVD uses DMA Modes. For the CD/DVD, I think this may have some bearing on the question: "80-Conductor Cable: For Ultra DMA modes over 2, an 80-conductor cable must be used. If an 80-conductor cable is not detected by the system, 66 MB/s or 100 MB/s operation will be disabled. " from DMA standards and definitions. Probably has a 40-wire cable on the CD/DVD...

 

thanks alot. Happy new year

 

when you change your SATA mode in bios from AHCI to Compatable, your HDD starts working in Ultra DMA mode through the SATA cable. Mine shows UDMA 5 on HD Tune.

 

That would explain why people complain of slower disk speeds in compatible mode. UDMA 5 is max 100 mbps, so you are losing 33% or 67% of your disk speed when running in compatible mode, depending on if you were running SATA or SATAII.

 

My Dell m1330 also shows UDMA mode 2 having a SATA disk.

By the way, how can I find out if my Dell m1330 supports SATA 3.0 capable hard disks in case I do an upgrade in the future?

 

Errr...no. The reason it reports Ultra DMA Mode 5 is because the SATA controller is using IDE compatibility mode.

SATA is 100% software compatible with IDE/ATA programming model (e.g. drivers, register set, firmware). All this means is that basic SATA does not require entirely new firmware and drivers, but can use existing firmware and drivers for IDE/ATA (with only minor modification to the firwmare). This was done to make adoption/transition easier with fewer bugs that would arise from completely new firmware, drivers, and register programming model.

This does not affect SATA transfer rate because the transfer rate is negotiated at the hardware level below any involvement of drivers and the operating system. However, it does limit some of the more advanced SATA features and configuration options, most of which may not even be supported by the hardware, anyway (NCQ, hot-plug, advanced power management, staggered spin-up, et. al.).

Because the controller is using the IDE/ATA register programming model, the system is only aware of Ultra DMA Modes supported by IDE/ATA. Therefore, the system can only report up to the highest Ultra DMA Mode supported by the controller. Intel ICH5 and later controllers support up to Ultra DMA 5 (100). On VIA VT8237 or other South Bridge that supports up to Ultra DMA 6 (133), the system would report Ultra DMA 6.

Again, this does not affect the transfer rate. The transfer rate is negotiated completely by the hardware (and firmware) without any involvement by the driver, just as Ultra DMA modes on ATA/IDE were entirely handled below the driver level. This is a reporting issue only.

To have SATA-specific support, the SATA controller must use 'native' SATA mode (e.g. AHCI) with a compatible driver and BIOS. Vista and Server 2008 support generic AHCI out-of-box with Microsoft drivers, but vendor-specific drivers may still be required to support all optional vendor-specific features. For XP/2000/2003, vendor-specific drivers are required (e.g. Intel drivers for Intel controllers, NVIDIA drivers for NVIDIA controllers, and so forth).