Discussion

SATA Write performance

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RobMeades replied at Fri Mar 20, 2015 09:51
Thanks for all of the excellent links and the detailed replies guys, they are very useful indeed.  I ...

If you had given all appropriate information at the beginning you would have got appropriate answers ;)

From what I guess now, you intend to store a few videos and the system must be powered by 5v only.

For that purpose I would use a pcArduino nano (because it has lowest cost about 35€) and add a 64G SDXC card which can be bought for 30€ or a small SSD which might cost more for the same size. Of course SDXC Card will be slow, but easy to use and power.

If you need less than 64GB, then only the SD-Card gives a really inexpensive solution, I would not use the on board flash RAM for that purpose.

tkaiser replied at Fri Mar 20, 2015 08:08
I can't give an explanation because I neither know why A20's SATA implementation or the drivers sh ...

Unfortunately I can not find any reference which would prove that tweaking the clocks really makes differences above a factor of 2.

If you enjoy playing around, that is your own hobby. But before recommending it to others one should

a) Verify what chips are used and what regions of safe operation are given by manufacturers.
b) Tweak not only the clocks but also the voltages to find out what maximum can be obtained.
c) Reduce clocks by a few percent to have some reserve.
d) Repeat such test with at least a dozen boards to make sure it was not a single shot.

tkaiser  
Edited by tkaiser at Sat Mar 21, 2015 06:44
LinAdmin replied at Sat Mar 21, 2015 04:43
I can not find any reference which would prove that tweaking the clocks really makes differences above a factor of 2


OMG! Noone ever wrote that. I just said that even if you increase the clock speed of the performance relevant parts (and unfortunately that's CPU and DRAM on A20 based boards) and adjust kernel config you won't exceed 45 MB/s SATA write speed on Allwinner platforms. Given the current driver situation (maybe that changes sometimes in the future maybe not).

tkaiser  
Edited by tkaiser at Sat Mar 21, 2015 06:53
LinAdmin replied at Sat Mar 21, 2015 04:09
For that purpose I would use a pcArduino nano ... and add a 64G SDXC card


If you refer to pcDuino nano then write speed to SD card will be limited to approx 15 MB/s with default settings and maxing out at 16.x MB/s (A10/A20 limitation). Not that much if one needs 50 - 70 MB/s?

tkaiser replied at Sat Mar 21, 2015 06:43
OMG! Noone ever wrote that. I just said that even if you increase the clock speed of the performan ...

It is not the first time that your understanding of English language is quite different from mine.
So let it be...

Well, all of the SBCs are pretty cheap so if I get it wrong I can always have another go.  Looks like SATA is most likely to solve my problems so a 5V powerable board with SATA SSD will be my starting point.  Thanks for all your help guys.

tkaiser  
Edited by tkaiser at Tue Mar 24, 2015 00:03
RobMeades replied at Mon Mar 23, 2015 15:27
Looks like SATA is most likely to solve my problems so a 5V powerable board with SATA SSD will be my starting point


But please keep in mind that anything with A10/A20 is limited to 40-45 MB/s SATA write speed (at least at the moment, if some of the driver developers from the linux-sunxi community would care and it's just a driver issue then this might be fixed sometimes in the future. I don't believe in that any longer since this hasn't changed for years and the 'benchmarks' posted sometimes are often the result of inappropriate use of tools like dd and/or hdparm:  https://groups.google.com/forum/#!topic/cubieboard/tD0AxHx5Ync)

I went for the Hummingboard i-2eX in the end.  Hopefully the drivers will be more able.

tkaiser  
RobMeades replied at Tue Mar 24, 2015 11:37
I went for the Hummingboard i-2eX in the end.  Hopefully the drivers will be more able.

You'll get +80/+100 MB/s write/read with SATA. But beware that this board has only an mSATA connector and while mSATA-to-SATA-adapters exist this won't address the SATA power problem if you want to use a 2.5" SSD (3.3V vs. 5V). The best choice would be a 840 EVO mSATA SSD since they're very power efficient too.

igorpec  
I can confirm +100MB/s read / write on Hummingboard i2ex with low cost msata SSD.

840EVO would be a luxury ;)

I read about troubles with some msata to sata converters so better stick to msata.

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