Quoting Gene Heskett (2019-09-18 21:19:45) > On Wednesday 18 September 2019 12:58:25 Jonas Smedegaard wrote: > > > Quoting Gene Heskett (2019-09-18 18:20:43) > > > > > On Wednesday 18 September 2019 11:36:41 John Hasler wrote: > > > > Jonas writes: > > > > > Please demonstrate just one single example of dd being faster > > > > > than cp to transfer a full raw image to a raw device! > > > > > > > > On modern systems you would probably need to be doing terabyte > > > > transfers between disks on the same machine. Back in the days > > > > when a megabyte was a lot dd was *much* faster. > > > > > > > > On an SD card I think that the write speed of the card is > > > > probably the limiting factor. > > > > > > It is, and the makers lie a lot, taking advantage of the buffering > > > to get thier 100 MBs rating for small writes. For gigabyte > > > transfers I often see sub 20 MB/S toward the end. But you may want > > > to steer clear of the 64GB+ cards, exfat is creeping into the sdhc > > > arena, and I either have a defective NEW PNY 64GB, or this stretch > > > install can't touch it because its exfat. I bought 2 recently, > > > same exact part number, slightly different card gfx, the 85 meg > > > rated one doesn't mention exfat, works, the 100 MB/S rated one > > > mentions exfat and is untouchable. > > > > Regarding quality of SD cards, I trust advices from Thomas Kaiser. > > > > Here's his advice on which brands to trust: > > > Only a few vendors on this planet run NAND flash memory fabs, only > > > a few companies produce flash memory controllers and have the > > > necessary know-how in house. And only a few combine their own NAND > > > flash with their own controllers to their own retail products. > > > That's the simple reason why at least I only buy SD cards from > > > these 4 brands: Samsung, SanDisk, Toshiba, Transcend > > > > Above quote is from > > https://forum.armbian.com/topic/954-sd-card-performance/page/3/?tab=comments#comment-49811 > > > > which is linked from front page intro to that thread - as part of > > this more general advice + warning not to waste time reading the > > whole > > > > thread: > > > Warning: This whole thread is only about historical information > > > now since it's 2018 and we can buy inexpensive and great > > > performing A1 rated SD cards in the meantime. Buying anything else > > > is a mistake so directly jump to the end of the thread for > > > performance numbers and recommendations. > > > > On a related note, here's Kaiser's more detailed notes on A1/A2 > > rating: > > https://github.com/ThomasKaiser/Knowledge/blob/master/articles/A1_and_A2_rated_SD_cards.md > > > That also seems to be somewhat dated. And rather Sandisk promoting.
No, quotes further up promotes brands closest to factories, and the article closes above promotes A1/A2 labeling which is brand-agnostic (yes, it proves its point by comparing cards from a single brand but that's besides the point). > So I bought another to see if they were still as bad as a year ago. Which brand and model? Did it have either "A1" or "A2" printed on it? What are the comparable results from same tests? They are linked from the article: https://github.com/ThomasKaiser/sbc-bench/blob/master/sd-card-bench.sh - Jonas -- * Jonas Smedegaard - idealist & Internet-arkitekt * Tlf.: +45 40843136 Website: http://dr.jones.dk/ [x] quote me freely [ ] ask before reusing [ ] keep private
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