They're slow as hell (far slower than a regular SATA HDD) and will often pretend the disk is uninitialized if the first partition isn't FAT32 or NTFS.

If you are using SATA with an adapters based on the FC1307A chip, it's only going to talk to the SD cards at Normal Speed (12.5MB/s) or High Speed (25MB/s).

That means if you use any SD card that was fabbed in the last 10 years, the SD->Sata adapter is going to be a performance limiting component.

They also don't take advantage of any of the new SSD like features either, so pairing these cheap adapters with an A2 rated SD is not likely to buy you any extra performance over an A1 rating.

Some adapters have a two chip solution, going SD->PATA->SATA. Those two step adapters are supposed to be notoriously poor performers, worse that you'd expect if you got a SD->PATA adapter and connected it to a Sata converter.

Here's what the two chip solutions look like--

I see some that do SD-->USB-->mSata. Those require that you set up a FAT32 partition in advance and seem to mount each partition as a separate drive. The added layer to the I/O stack also perform slowly.

I did some reading up on this matter because I bought a Raspberry Pi, and those use a MicroSD for mass storage. Apparently normal consumer MicroSD drives, because of their firmware, are likely to get trashed if a system is turned off improperly/during a write operation. They also tend to have a surprisingly poor lifetime under heavy rewriting and generally poor error correction. They're only intended for storing data, and relatively unimportant data at that. Plus, even if they sustain high speeds on linear access of large files, they're quite slow on small files/random reads and writes.

You can get industrial grade one from Mouser, Farnel .etc. Still pretty cheap, I paid $30 for a 16Gb true SLC Sandisk device that is actually intended for use as a boot device in embedded and industrial applications. But I wouldn't use it on anything like a modern desktop... the Raspberry Pi Zero I'm using has about the power of a Pentium 3 500, and even there garbage cards seriously affect disk performance.