The smaller cheaper controllers erase big blocks of data, perhaps 128 KB, which means a 1 KB file write uses 128 KB. When you change the 1 KB file, a 128 KB block is erased then written to. The previous 128 GB block goes of for an erase. The monster wastage is called write amplification and is one cause of fast failure. A better controller might erase in 8 KB blocks.
The A1 standard requires fast write of 4 KB blocks which means a bigger controller as the same size storage requires the processing of more blocks. One 128 GB block has to be handled as 32 * 4 KB blocks. Smaller updates. Less wear overall. Also faster and less heat. The 1 KB write requires the erase of only 4 KB, not 128 KB. A1 is the perfect match for the Ext4 file system.
The A2 cards add command queuing and caching, just like SSDs. It might make some things faster but does not alter wear. A few months ago, the Pi computers did not make use of A2. I buy A2 because they are now the same price as good A1 cards. Plus the A2 speed rating means the card is the latest revision, not old stock.
I found a page listing a very detailed testing procedure for detecting fakes. Using programs that run only on Windows.![:o]( "Surprised")
I am thinking about using the test when I buy a 32 TB microSD from China for $1.98 including postage.![:D]( "Very Happy")
The A1 standard requires fast write of 4 KB blocks which means a bigger controller as the same size storage requires the processing of more blocks. One 128 GB block has to be handled as 32 * 4 KB blocks. Smaller updates. Less wear overall. Also faster and less heat. The 1 KB write requires the erase of only 4 KB, not 128 KB. A1 is the perfect match for the Ext4 file system.
The A2 cards add command queuing and caching, just like SSDs. It might make some things faster but does not alter wear. A few months ago, the Pi computers did not make use of A2. I buy A2 because they are now the same price as good A1 cards. Plus the A2 speed rating means the card is the latest revision, not old stock.
I found a page listing a very detailed testing procedure for detecting fakes. Using programs that run only on Windows.
I am thinking about using the test when I buy a 32 TB microSD from China for $1.98 including postage.
Statistics: Posted by peterlite — Wed Sep 04, 2024 11:24 pm