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#31
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SATA vs. IDE
On Mon, 4 Aug 2003 12:51:26 -0700
Bill wrote: In article , says... snip You've snipped who said what, but I think it was me that said... Scsi doesn't have DMA. AS far as I know, neither does SATA. Hmmm....SCSI has had DMA transfers for at least the last 15 years. My all SCSI systems use DMA and this is set from the SCSI BIOS (no doubt Windows also has the DMA settings switch and, not being a Win user I would have to experiment to see if Win ignored the BIOS settings or not. No doubt another person could advise better on this. I don't know whether Scsi handles memory transfers through DMA or some other mechanism, so I'll take your word for it. I'm running SATA on a Asus A7N8X Deluxe Ver. 1.06 MB and a Promise Fasttrak 100 Raid controller in Raid 0+1 and neither show a DMA box under Device Manager; both show as Scsi devices Win2000 . It would have been more correct of me to say that, afaik, Windows up to 2000, never ran XP, has no mechanism for enabling/disabling DMA tranfers that I've ever found in Scsi devices, under Device Manager. That's because with SCSI host adapters you don't enable or disable DMA any more than you would do it with a network card or video board. With IDE drives, you enable or disable because the driver is one-size-fits-all and some drives have DMA while others don't. With SCSI DMA is on the host adapter, not the drive, and is handled by a device driver unique to that host adapter rather than a generic driver, hence no need to enable or disable. Whether SCSI has or does not have DMA then depends on the particular host adapter--a cheap one won't, a good one will. I do have a box with a Tekram DC-395U Scsi controller but it's in pieces getting a new Abit NF7-S MB installed, and used to have a Fireport 40. I don't remember seeing DMA under either of the the bios areas for these controllers. Could it be that DMA is only on faster Ultra80/Ultra160/Ultra320 controllers? Or goes by a different name? No, it's something that you don't futz with--there's no setting for it, it's built into the hardware and drivers. According to Tekram the DC-395U is a "Full 32-bit PCI DMA bus master", which means that it uses DMA. Bill Regards, Kevin -- -- --John Reply to jclarke at ae tee tee global dot net (was jclarke at eye bee em dot net) |
#32
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SATA vs. IDE
J.Clarke wrote:
That's because with SCSI host adapters you don't enable or disable DMA any more than you would do it with a network card or video board. With IDE drives, you enable or disable because the driver is one-size-fits-all and some drives have DMA while others don't. With SCSI DMA is on the host adapter, not the drive, and is handled by a device driver unique to that host adapter rather than a generic driver, hence no need to enable or disable. Good explanation John, Ben -- I'm not just a number. To many, I'm known as a string... |
#33
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SATA vs. IDE
On Thu, 17 Jul 2003 07:59:06 +0100, "Ben Pope"
wrote: Ransack The Elder wrote: "Ben Pope" wrote in message ... You're missing the point. Before you can say This SATA drive is worse than that PATA drive, you need to be taking into account the actual drive, not just its interface, not just the manufacturer. 1) I have the fastest 120 gig SATA drive on the market..today, anyway. OK, but it's still not native SATA. 2) Everything I have read and all the charts I have seen say that SATA is faster than IDE. Read more. 3) My IDE drives are faster than my SATA drive. OK. So, does that mean: A) My IDE drive are that damn good. Yes. BUt because it's a fast drive mechanism and good algorithms, not because it's PATA. B) SATA is marketing hype that offers nothing other than a smaller cable. No! It offers many useful things such as hot-plugging. I don't know how many times that would have been useful for me, at least, Now, what you have is NOT a native SATA drive, you have a PATA drive with a PATA to SATA convertor chip on it - this may explain why you have experienced some degradation in peformance over the IBM drive. Additionally, whereas your ATA interface is built directly into your chipset, your the data flowing through your SATA interface has to also traverse the PCI bus (limited in TOTAL to 133Megs/s). Ummm..okay...so let's say my SATA controller is NOT built onto my chipset. I would need a PCI SATA card which...bada bing...traverses the PCI bus. So what's the difference????? Re-read what I said. Do you still think you are performing a fair comparison of SATA and PATA? Yep. I have the same setup as those two websites you sent. Ok, then do you think that THEY were performing a fair comparison? Before suggesting that SATA is worse than PATA we will have to wait for chipsets and drives to natively support SATA, neither of which are true for your system, but both of which are true for PATA on your system. So after all that you're saying that I'm right. Right now, SATA is no better than PATA. Yes. I never disagreed with you on the end result, all I was saying was that SATA is not inferior merely because in your system PATA happens to be faster - I'm saying that it's a result of the drive mechanics NOT the interface. I've said all along that the performance of a drive is not entirely a result of the interface it uses to connect to the computer. If a drive can do 70Megs/s max, then it can do 70Megs/s oer SCSI, SATA, PATA (ATA/100, ATA/133)... Ben |
#34
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SATA vs. IDE
On Sat, 23 Aug 2003 07:02:51 -0700, vegan
wrote: On Thu, 17 Jul 2003 07:59:06 +0100, "Ben Pope" wrote: Ransack The Elder wrote: "Ben Pope" wrote in message ... You're missing the point. Before you can say This SATA drive is worse than that PATA drive, you need to be taking into account the actual drive, not just its interface, not just the manufacturer. 1) I have the fastest 120 gig SATA drive on the market..today, anyway. OK, but it's still not native SATA. 2) Everything I have read and all the charts I have seen say that SATA is faster than IDE. Read more. 3) My IDE drives are faster than my SATA drive. OK. So, does that mean: A) My IDE drive are that damn good. Yes. BUt because it's a fast drive mechanism and good algorithms, not because it's PATA. B) SATA is marketing hype that offers nothing other than a smaller cable. No! It offers many useful things such as hot-plugging. I don't know how many times that would have been useful for me, at least, Now, what you have is NOT a native SATA drive, you have a PATA drive with a PATA to SATA convertor chip on it - this may explain why you have experienced some degradation in peformance over the IBM drive. Additionally, whereas your ATA interface is built directly into your chipset, your the data flowing through your SATA interface has to also traverse the PCI bus (limited in TOTAL to 133Megs/s). Ummm..okay...so let's say my SATA controller is NOT built onto my chipset. I would need a PCI SATA card which...bada bing...traverses the PCI bus. So what's the difference????? Re-read what I said. Do you still think you are performing a fair comparison of SATA and PATA? Yep. I have the same setup as those two websites you sent. Ok, then do you think that THEY were performing a fair comparison? Before suggesting that SATA is worse than PATA we will have to wait for chipsets and drives to natively support SATA, neither of which are true for your system, but both of which are true for PATA on your system. So after all that you're saying that I'm right. Right now, SATA is no better than PATA. Yes. I never disagreed with you on the end result, all I was saying was that SATA is not inferior merely because in your system PATA happens to be faster - I'm saying that it's a result of the drive mechanics NOT the interface. I've said all along that the performance of a drive is not entirely a result of the interface it uses to connect to the computer. If a drive can do 70Megs/s max, then it can do 70Megs/s oer SCSI, SATA, PATA (ATA/100, ATA/133)... Ben |
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