ATA troubles

perryh at perryh at
Mon Jul 25 21:39:59 UTC 2011

Andrea Venturoli <ml at> wrote:
> On 07/25/11 16:03, perryh at wrote:
> > I fixed a similar problem -- involving a VIA 6421 controller --
> > a while back, by using atacontrol(8) to reduce the DMA speed
> > from UDMA133 to UDMA100.
> ...
> I don't know if this is really effective with SATA...

Nor do I; my problem involved a PATA device.

Dmesg reports for SATA devices include a UDMAxx notation in addition
to the SATA speed notation, but I don't know its significance.

ad0: 305245MB <Hitachi HDT725032VLAT80 V54OA4NA> at ata0-master
ad1: 32253MB <MAXTOR 6L040L2 A93.0500> at ata0-slave UDMA66 
ad4: 61136MB <PATRIOT MEMORY 64GB SSD 02.10104> at ata2-master
     UDMA100 SATA 1.5Gb/s
acd1: DVDR <PIONEER DVD-RW DVR-212D/1.24> at ata3-master
     UDMA66 SATA 1.5Gb/s
ad8: 305245MB <Hitachi HDT725032VLAT80 V54OA4NA> at ata4-master

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