- May 11, 2008
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I've been saving benchmarks of the storage devices I come across using CrystalDiskMark, HDTune and HDDScan. So far memory cards make up only a small part of the database.
The tested memory cards are mostly old ones of low capacity (16MB to 2GB), so I didn't pay much heed to the low speeds I got. But I got a surprise when I tested a new 32GB uSD card a few days ago. It's a SanDisk Ultra UHS-1, the "Up to 80MB/s" version. I did the test on a USB 3.0 port but with a USB 2 card reader, so I expected to get something like 40 MB/s sequential read speed. But I was shocked to see that it never rose much above 8MB/s. Stranger still was that the write speed was more than double the read speed at ~19MB/s.
Real-world copying of a 1GB file returned the same results.
To check for the possibility of a misbehaving USB port, I plugged in my SanDisk Extreme USB 3.0 thumb drive and got the same 200MB/s read and 120MB/s write speeds (rounded off) as on earlier tests.
Thinking that the card reader - a cheap Chinese product - might be causing a bottleneck, I repeated the tests with two different Transcend readers, but the results were the same. Then I pulled out a 16GB card of the same model from a phone and ran the benchmark tests. It showed the same sequential read speed of about 8MB/s.
Can anyone please offer a possible explanation for the pathetic read speeds?
The tested memory cards are mostly old ones of low capacity (16MB to 2GB), so I didn't pay much heed to the low speeds I got. But I got a surprise when I tested a new 32GB uSD card a few days ago. It's a SanDisk Ultra UHS-1, the "Up to 80MB/s" version. I did the test on a USB 3.0 port but with a USB 2 card reader, so I expected to get something like 40 MB/s sequential read speed. But I was shocked to see that it never rose much above 8MB/s. Stranger still was that the write speed was more than double the read speed at ~19MB/s.
Real-world copying of a 1GB file returned the same results.
To check for the possibility of a misbehaving USB port, I plugged in my SanDisk Extreme USB 3.0 thumb drive and got the same 200MB/s read and 120MB/s write speeds (rounded off) as on earlier tests.
Thinking that the card reader - a cheap Chinese product - might be causing a bottleneck, I repeated the tests with two different Transcend readers, but the results were the same. Then I pulled out a 16GB card of the same model from a phone and ran the benchmark tests. It showed the same sequential read speed of about 8MB/s.
Can anyone please offer a possible explanation for the pathetic read speeds?
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