Q & A – Disk/Drive/CD-ROM/DVD/Tape Detection

This document provides some frequently asked questions about Sandra. Please read the Help File as well!

Q: Sandra cannot see my ATAPI devices or the controllers that have only ATAPI drives connected to them!
This is a known bug in the ATA/ATAPI Windows miniport; upgrade to Windows 2003, Windows XP/SP2 to fix this issue.

Q: Sandra tells me my disk is in UDMA-x mode. What ATA mode is that?
Each UDMA mode corresponds to the following ATA modes:

  • SWDMA-x & MWDMA-x = ATA – Max 16MB/s
  • UDMA-0/1/2 = ATA33 – Max 33MB/s
  • UDMA-3/4 = ATA66 – Max 66MB/s
  • UDMA-5 = ATA100 – Max 100MB/s (PCI64/66/X recommended)
  • UDMA-6 = ATA133 – Max 133MB/s (PCI64/66/X recommended)
  • UDMA-x = ATA150 (Serial ATA) – Max 150MB/s (PCI64/66/X recommended)

Q: Sandra tells me my ATAxx drive is using 16-bit wide transfers. It should be 32-bit!
No, the hardware interface to ATAxx devices is 16-bit wide only (40/80 pin cable). This has nothing to do with the device driver.

Q: My drive seems to be in PIO mode instead of UDMA mode. What can I do?
Make sure you install the proper device drivers for your UDMA controller and that DMA/UDMA is enabled. Generally ATAPI devices are driven in PIO mode by default even if they support DMA/UDMA modes (for compatibility). Make sure you force them in DMA/UDMA mode.

Q: My drive/RAID array is in ATA133 mode but gets no better performance than ATA100 mode!
Most PCI33 interfaces are limited to ~90MB/s due to bus contention and overheads. PCI 64-bit/66MHz/X adapters are recommended to get the best of the ATA interface.

Q: My drive is ATA66/100/133 but seems to run in ATA33 mode only!
Make sure you use a 80 pin ATA cable and that it is installed correctly. If you use cable select, try forcing Master/Slave modes as appropriate. If you have an ATA33 drive or ATAPI device on the same cable, try with just the ATA66/100 drive.

Q: How do I get information about my individual drives of my RAID array in Sandra?
You cannot, use the diagnostic/information utility for your RAID controller. The drives cannot be individually addressed in order to maintain consistency of the RAID array.

Q: If I use a 80 pin cable will I be be able to use 32-bit wide transfers?
No, 80 pin cable is to enable ATA66/100/133 modes, not ultra-wide transfer modes.

Q: My ATAPI drive (CD-ROM, ATAPI ZIP, etc.) is detected as a SCSI drive or my SCSI drive is detected as an IDE/EIDE device!
Iomega’s ATAPI ZIP manual says at page 4 (Windows NT installation): “Note: Windows NT installs drives or adapters that use the IDE interface as SCSI adapters“. However, they seem to be a bit economical with the truth. It should say: “Note: Windows installs drivers or adapters that use the ATAPI interface as SCSI adapters“. This makes sense since ATAPI is quite similar in many ways to SCSI, but this
adds to the confusion. There is no (easy) way to determine whether a device is really ATAPI or SCSI in Windows at high-level.


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