Messages in this thread | | | Date | Tue, 1 Jan 2002 15:32:16 -0800 (PST) | From | Andre Hedrick <> | Subject | Re: Two hdds on one channel - why so slow? |
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Brian,
Well if hell freezes over and I die, the patches to make the driver handled clean low_level IO threading will never be accepted. Because they model the state-diagrams of the physical layer of the hardware exactly in the transport layer, it is totally orthoginal to the darwinism of Linux. Design is a problem, it is not permitted in a darwin-evolution model.
It only allows you to access both drives on a channel and only suffer a 10% IO loss max on each, but you gain a smooth IO access to both drives.
Regards,
Andre Hedrick CEO/President, LAD Storage Consulting Group Linux ATA Development Linux Disk Certification Project
On Tue, 1 Jan 2002, Brian wrote:
> This is an inherent quirk (SCSI folks would say brain damage) in IDE. > > Only one drive on an IDE chain may be accessed at once and only one > request may go to that drive at a time. Therefore, the maximum you could > hope for in that test is half speed on each. Throw in the overhead of > continuously hopping between them and 12MB is no surprise. > > That is why even cheapo Compaqs and Gateways have the hard drive and > CD-ROM on separate chains. It's also why IDE RAID cards have a separate > connector for each drive. > > -- Brian > > On Tuesday 01 January 2002 05:34 pm, Krzysztof Oledzki wrote: > > Hello, > > > > There is something wrong with ide data throughput with at last both via > > kt133 and promise pcd20265 controllers. > > > > I have Asus A7V-133 Mobo with VIA KT133A chipset and onboard Promise > > pcd20265 ide controller. My CPU is Athlon 1400 MHz and I have 512 MB of > > PC133 SDRAM. I noticed that connecting two ata100 hdds into the same > > channel makes everything much slower. So I made some test: > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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