30 March 2019, 23:10 | #1 |
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Max Transfer rates help
after swapping out my cheap chinese 16gb CF card for a 16gb Sandisk , i was checking the max transfer settings via hd toolbox and they are as follows.
DH0:PFS\03 Mask 0x7ffffffe MaxTransfer 0x1fe00 block size 512 DH1:PFS\03 Mask 0x7ffffffe MaxTransfer 0xffffff block size 512 DH2:PFS\03 Mask 0x7ffffffe MaxTransfer 0xffffff block size 512 DH3:PFS\03 Mask 0x7ffffffe MaxTransfer 0xffffff block size 512 been reading around and to say the least its rather confusing for a n00b lol should the max transfer be the same on all drives ? or just the boot drive DH0: ? blocksize of 512 ok on all drives? seems to b the default.. everything seems to be working just fine, but be nice to know its getting best speed it can. and it seems to be on PFS\03 v19.2 i think. any suggestions to improve here or is it all fine as is? thanks muchly |
30 March 2019, 23:18 | #2 |
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In a nutshell. Set all drives to the correct max transfer value. This is needed due to read times being much faster on CF/SD card in comparison to mechanical drives.
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31 March 2019, 09:49 | #3 |
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This is needed to circumvent a change in the IDE command specification that older versions of scsi.device do not know about. It has to do with transferring of large blocks of data in one IDE command.
If you have an old scsi.device and have the incorrect max transfer size, you will get data corruption. It's a good idea to adjust it even with the OS3.1.4 scsi.device. |
31 March 2019, 10:03 | #4 |
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First of all MaxTransfer is not a rate, it is a chunk size. It has nothing to do with speed.
Mask and MaxTransfer are controller attributes, so they should be set to the same value on all partitions. |
31 March 2019, 11:12 | #5 | |
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Quote:
Never had one crash on this system in over 12 months so I leave mine as is |
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31 March 2019, 11:35 | #6 |
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Awesome. I take it the CF you sent me has the latest FS
I hadn't known that it was for file chunks. I thought it was literally to correct speed lol |
31 March 2019, 11:46 | #7 |
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31 March 2019, 11:51 | #8 |
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31 March 2019, 13:00 | #9 |
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Why? Just tell me why... MaxTransfer is only required for broken drivers or broken hardware. If you have an indication that the Os 3.1.4 scsi.device *requires* maxtransfer to operate properly, I would be curious to know. In general: *Do not touch these values*. They can only make the I/O transfer slower, not faster.
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31 March 2019, 13:18 | #10 | |
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If someone knows what they're doing, they are not asking questions anyway, and know where the maxtransfer will and will not be a problem. I am aware of 3.1.4 having this issue fixed, but was too lazy to be more verbose when posting. |
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31 March 2019, 13:46 | #11 | |
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From the PFS3 documentation on MaxTransfer:
Quote:
How do we know the maximum that a compact flash card can handle? I'm sure this info was probably hard enough to find back in the days of 90's spinning disks. Or alternatively, is this documentation out of date and all this is no longer needed which is what people seem to be saying here? |
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31 March 2019, 13:49 | #12 | |
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Quote:
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31 March 2019, 13:52 | #13 |
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Ah cool, thanks.
So basically given then that the info about masks and interfaces is also in that documentation, coupled with being able to use that tool, it's going to be possible to know you've got decent values in there regardless of whether they are ignored or taken into account, like you say, good if you were to move the CF card around or install a different version of OS without re-partitioning. |
31 March 2019, 14:32 | #14 |
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Sorry, one question - where is maxtransfertest? I don't see it on Aminet. Apologies if I'm being thick!
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31 March 2019, 14:45 | #15 |
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https://thomas-rapp.homepage.t-online.de/download.html maxtranstest.lha
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31 March 2019, 15:13 | #16 |
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Just to clarify, by "device", the documentation will generally be referring to the device driver (e.g. scsi.device), not the physical hardware. So you don't need to worry about CF cards etc., just what the driver can handle.
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31 March 2019, 15:26 | #17 |
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Where's that 'slaps forehead' icon when you need it
Thanks for that I have to say that after my reading earlier in the week and stumbling across this thread I finally feel like I have a proper grasp on the settings. Hopefully other people will feel the same. It's only taken me about 10 years. |
31 March 2019, 16:01 | #18 |
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You don't need to know. Really. An IDE device has to be able to read 255 blocks (yes, really 255) through one command. The *only* reason why you had to set a mask is because the 3.1 scsi.device had this limit wrong (256 instead of 255). MaxTransfer is *not* dependent on the hardware. As said, it *only* works around faulty device drivers. Same as Mask and BufMemType. A non-broken device driver can take any memory type and any buffer alignment.
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31 March 2019, 16:14 | #19 | |
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Actually 256 is correct. There is a one byte length field and 0 means 256.
The problem is something else. After reading or writing 256 sectors scsi.device expects some registers have automatically changed which was true by the old ATA specs, but is no longer in the new specs. Toni Wilen found the details, there is a thread about it somewhere on this forum. Edit: here is a quote from the ATA-2 specs: Quote:
Last edited by thomas; 31 March 2019 at 16:26. |
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31 March 2019, 16:16 | #20 |
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