Lexar Professional 1000x 64GB

• Obtained from: Amazon
• Advertised capacity: 64GB
• Fake/skimpy flash: No
• Protected area: 134,217,728 bytes
• Speed class markings: Class 10, U3

Card #	1	2	3	Average
Price paid	$13.99	$12.99	$11.95	$12.98
Logical capacity	64,087,916,544 bytes	64,087,916,544 bytes	64,172,851,200 bytes	64,116,228,096 bytes
Physical capacity	64,087,916,544 bytes	64,087,916,544 bytes	64,172,851,200 bytes	64,116,228,096 bytes
Adjusted skimp	-0.35%	-0.35%	-0.48%	-0.39%
Manufacturer ID	0x28*	0x28*	0x27**	N/A
OEM ID	0x4245 (ASCII: BE)*	0x4245 (ASCII: BE)*	0x5048 (ASCII: PH)**	N/A
Product name	0x363842484f (ASCII: 68BHO)	0x363842484f (ASCII: 68BHO)	0x3659444c50 (ASCII: 6YDLP)	N/A
Product revision	0x08	0x08	0x07	N/A
Manufacture date	Jan 2017	Feb 2017	Apr 2017	N/A
Serial number	0x663b0e7f	0x863b1c8f	0xda874480	N/A
Sequential read speed (MB/sec)	164.16	170.52	151.99	162.22
Sequential write speed (MB/sec)	35.49	35.89	49.97	40.45
Random read speed (IOPS/sec)	2883.53	1,050.90	2,336.09	2,090.17
Random write speed (IOPS/sec)	125.79	231.28	584.21	313.76
Read/write cycles to first error	0	0	163	54
Read/write cycles to complete failure	Not yet determined	Not yet determined	Not yet determined	Not yet determined
Total days to complete failure	Not yet determined	Not yet determined	Not yet determined	Not yet determined
Card reader used	Lexar LRWM05U-7000	JJS CR-UTC4AC	JJS CR-UTC4AC	N/A
Package front				N/A
Package back				N/A
Card front				N/A
Card back				N/A

* This manufacturer ID/OEM ID combination is pretty well known to be associated with Lexar.

** This manufacturer ID/OEM ID combination is pretty well known to be associated with Phison.

Discussion

Oh boy, do I have a thing or two to say about these cards. So here we go.

I purchased sample #1 because I wanted to be able to have at least one UHS-II card in my results. UHS-II cards tend to be pretty expensive (comparatively speaking), which is why I initially only ordered one. It came in retail packaging, complete with a Lexar LRWM05U-7000 UHS-II card reader, and I initially planned to test it with this card reader — but fate (or Lexar?) apparently had other ideas. It almost immediately had issues, unable to make it through even its authenticity or performance tests. After a few tries, I was able to get it to complete both tests — but I found that it was much more stable when I switched it over to another reader, so I gave up on the Lexar LRWM05U-7000 and put it into a JJS CR-UTC4AC instead.

I bought the first of these cards because I wanted to be able to have at least one UHS-II card in my results. UHS-II cards tend to be pretty expensive (comparatively speaking), so I initially only ordered one. It arrived in retail packaging, which included a Lexar LRWM05U-7000 UHS-II card reader. I planned to test it using this card reader; however, it started to experience I/O errors soon after tests began. On the next attempt, I was able to get it to complete its authenticity and performance tests; but it then started experiencing I/O errors during the first round of endurance testing. Restarting the endurance test didn’t seem to help — so I decided to move it to one of the JJS CR-UTC4ACs instead.

The I/O errors stopped under the JJS reader, but then a different issue surfaced: in every round of the endurance test, there would be a handful of data verification failures. But when I looked at the data being read back and compared it to what was being written to the card, I noticed something odd. Here’s a snippet of my logs — see if you can spot the issue:

And another mismatch that happened a couple weeks later:

See that? It’s always bytes 16-19 that are mismatched. Every. Single. Time.

“OK”, I thought to myself, “maybe I just got a bad card. It happens. I’ll just order another one.” So I did, and from the same Amazon seller. This one looked pretty much identical to the first one, complete with another Lexar LRWM05U-7000 card reader. This time, I decided to set that one aside, and I put it straight into one of the JJS CR-UTC4AC readers. And as soon as the endurance test started running? It started having the same issue — right down to the same four bytes being mismatched:

This was too weird to be coincidence. I considered that maybe they were both part of the same batch, and that there was an issue with that particular batch — but the two cards have different manufacturing dates (and wildly different serial numbers). That means that either there was a manufacturing issue that went undetected for multiple batches, or there’s a design flaw with this card.

For a while, I was going to leave it at that; but at some point, I decided that I should try to have at least three samples of all the cards I’m testing — so I went back to the same Amazon seller and ordered a third one. Here’s where the story took a twist: the product packaging was identical, it included another Lexar LRWM05U-7000 card reader, the card design was the same — but the CID data indicates that it’s a completely different card! Every single field in the CID register was different from the other two samples. The manufacturer ID indicates that it was made by Phison — which has been known to make Lexar-branded cards in the past (at least, according to CameraMemorySpeed.com) — so my guess is that Lexar simply contracted out part of the production of these cards to Phison.

The package advertises read speeds of up to 150MB/sec and write speeds of up to 45MB/sec. All three samples managed to surpass 150MB/sec on sequential read speeds (putting it more than one standard deviation above average, with two of the samples scoring more than two standard deviations above average), but only sample #3 (the Phison-produced sample) managed to hit the 45MB/sec mark on sequential write speeds. Samples #1 and #2 ended up being just slightly above average in this category, while sample #3 ended up being more than one standard deviation above average.

Random I/O speeds were pretty inconsistent. When tested with the Lexar LRWM05U-7000, sample #1 got random read speeds that were more than one standard deviation above average. However, the same card, tested on the same machine with a JJS CR-UTC4AC, only managed to get about 1/4 of that. Both random read speeds and random write speeds ran the gamut from “well below average” to “more than one standard deviation above average”, depending on the card. I can’t say for sure whether the Phison-produced samples or the Lexar-produced samples were better for random read speeds, but it did seem like the Phison-produced sample was significantly better for random write speeds.

All three samples scored well enough to merit the Class 10 and U3 markings; but frankly, I would have expected better for a name-brand card that had “Professional” as part of its name — especially when there are UHS-I cards that were able to perform better.

All three samples are still undergoing endurance testing:

• Sample #1 has survived 2,587 read/write cycles so far.
• Sample #2 has survived 3,666 read/write cycles so far. (I find it curious that sample #2 has outpaced sample #1 — they’re both hooked up to the same machine, to identical card readers. However, sample #1 is averaging about 9.14 read/write cycles per day, while sample #2 is averaging about 14.85 read/write cycles per day. I don’t know why.)
• Sample #3 has survived 2,104 read/write cycles so far.

Of course, there’s one more strangeness to add to this whole thing: by round 294, the errors with sample #1 stopped completely, and did not recur until round 988. Did the card’s wear leveling algorithm simply rotate these bad sectors out into its spare space for those intervening 700-ish rounds? Or was some other factor at work here? (It’s times like these that make me wish I could see into what’s going on inside the microSD card…) Meanwhile, sample #2 is still turning up a handful of errors almost every round.

The Phison-produced sample, on the other hand, has not had quite the same issues that the Lexar-produced samples did. This sample managed to go 163 read/write cycles before its first error — a four-sector wide address decoding error. It experienced another address decoding error — this time affecting six sectors — during round 173, but has not experienced any further errors since then.

Overall, however, I wouldn’t recommend buying this card. While some of the performance metrics were good-to-impressive, it doesn’t make up for the data integrity issues that I encountered on the two Lexar-produced samples. As evidenced by the fact that I bought all three samples from the same seller and got two different cards, I think it’s fair to say that if you purchased one of these, there would be no way of knowing beforehand whether you were going to get a Lexar-produced card or a Phison-produced card. Had I used this in a digital camera and gone on a photo shoot, it’s likely that some of my pictures would have been corrupted the very first time I used the card — and any photographer will tell you that’s just not acceptable.

June 15, 2024 (current number of read/write cycles is updated automatically every hour)