A pair of known-good MicroSD cards arrived direct from Samsung at a surprisingly slight premium over the junk available on Amazon:
f3probe reported they’re OK, which is no surprise:
sudo f3probe --time-ops /dev/sdc F3 probe 6.0 Copyright (C) 2010 Digirati Internet LTDA. This is free software; see the source for copying conditions. WARNING: Probing normally takes from a few seconds to 15 minutes, but it can take longer. Please be patient. Probe finished, recovering blocks... Done Good news: The device `/dev/sdc' is the real thing Device geometry: *Usable* size: 29.81 GB (62521344 blocks) Announced size: 29.81 GB (62521344 blocks) Module: 32.00 GB (2^35 Bytes) Approximate cache size: 0.00 Byte (0 blocks), need-reset=no Physical block size: 512.00 Byte (2^9 Bytes) Probe time: 2'04" Operation: total time / count = avg time Read: 51.79s / 4197134 = 12us Write: 1'10" / 4192321 = 16us Reset: 1.41s / 1 = 1.41s
These will go into Raspberry Pi projects, where their huge capacity won’t produce any benefit. It seems one can’t get known-good, small cards these days.
I don’t see much point in buying known-crap counterfeits on Amazon, given their commingled-storage problem as pointed out by their helpful FBA advice:
Use the manufacturer barcode to track inventory
By default, your seller account is set to use the manufacturer barcode to track your eligible inventory throughout the Amazon fulfillment process. You can change this default barcode preference at any time. You have the option to change your barcode preference for each offer you create. You can also change your barcode preference for a product when you change a listing from Fulfilled by Merchant to Fulfilled by Amazon.
Important: Items in your inventory that are identified and tracked using manufacturer barcodes are commingled with items of the same products from other sellers who also use manufacturer barcodes for those items.
If you choose to use manufacturer barcodes, when customers purchase a product from you, Amazon can send the item that is closest to them, even if you didn’t send it to the fulfillment center. When that happens, you get the credit for the sale, and we transfer an item from your inventory to the seller whose inventory was used to fulfill the order. In addition, if you use the manufacturer barcode, you don’t have to apply an Amazon barcode to each item yourself.
Even though inventory tracked using the manufacturer barcode is commingled within the network, the source of the inventory is tracked by our fulfillment systems and is taken into consideration if inventory problems arise.