SUMMARY: DMA (IDE) on Solaris

From: Santos, Ramiro <>
Date: Mon May 06 2002 - 05:30:55 EDT
normaly people don4t use IDE based systems but unfortunately sun sells such
like Ultra 5, Ultra 10, Blade 100 and so on...
As a desktop system they are fine, but not performant.
Here is what I found about DMA on Solaris

> The ultra 5/10 models do not use udma or dma of any kind with regards to
> the ide implementation, PIO mode is used.  The blade workstations
> utilize the udma functionality.  The chipset for u5 -u10 is the older
> cmd640 without any bus mastering enhancements present.  Get a symbios
> 53c875spe card from ebay and go scsi for performance on these boxes.

> The CMD640 doesn't support UDMA but the CMD646B does. I've no idea
> what's inside of the currently shipping Ultra 10s, but four years ago
> I was explicitly told by the Sun engineer who ported and updated my x86
> ata driver to the SPARC to support and enable UDMA mode, that Sun was
> going to ship Ultra 10s with the CMD646 chip. The SPARC ata driver isn't
> as clean and robust as the x86 ata driver but I'm certain (unless some
> Sun engineer has recently patched the driver to disable it) that they
> both support UDMA mode on UDMA-capable hardware. Unfortunately, I'm not
> certain but it's possible that some of the U5/10 CDROM drives Sun sold
> do not support UDMA mode, and therefore do all CDROM I/O transfers in
> PIO mode (i.e., only the hard disk runs in UDMA mode). A CDROM drive
> running in PIO mode will cause a high CPU load (not a high I/O load).
> You could try checking the model number of your CDROM against the
> specs published by the drive vendor to see if it's UDMA-capable.

Many thanks to Richard Eisenman

Yours sincerely,

Ramiro Santos

ZIT P 7.41 Unix Server Implementation


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Received on Mon May 6 05:36:21 2002

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