Sandisk 32gb Extreme Plus UHS-1 U3 sd card review & test

[catchingup]

I tested the current Sandisk 32gb Extreme Plus micro sd, uhs-1 U3 inside our F6 phone.


Summary:

• Holy sh** it's fast.
• The F6 sd card reader can push faster than the eMMC.
• Inside the F6, the Extreme+ blows 32gb Samsung EVO away, with ~60% faster sequential read and ~95% faster sequential write. Random r/w speeds are the same between both cards based on limited benchmark, but huge amounts of random data may show Sandisk coming out ahead.
  
• PC to phone transfers still slow over usb cable, so you'll need to pull the card out and use a UHS-1 reader for the fastest transfers. Sandisk Ex+ transfers faster from PC to phone, but Samsung EVO may read faster from phone to PC.
  
• Real world performance difference negligible.

Details:

A1 SD BENCH for sandisk extreme+
random i/o:
18.04 / 2.29 MB/s test1 fat32
16.66 / 1.79 MB/s test2 fat32
17.69 / 1.85 MB/s test3 fat32
16.36 / 0.71 ext4. multiple tests. Hmm.... ext4 write is much slower than fat32
15.64/0.85 ext4

Accurate:
57.75 / 29.46 fat32
57.89 / 27.56 ext4

A1 SD Bench for eMMC
random i/o:
19.31 / 0.2

accurate:
43.78 / 12.81

A1 SD Bench for Samsung EVO:
Random i/o:
15.49/0.72 ext4
13.55/0.58 ext4
17.22/0.76 ext4
17.41/1.97 fat32

Accurate:
35.7/9.09 ext4
34.3/14.1 ext4
35.8/14.94 fat32
-----------------------------------------------------------

In actual phone usage....
WV sd hack copying step to sd card much faster.
Apps load as fast as (or maybe even a hair faster than) eMMC, though the eMMC and samsung evo are no slouch either when it comes to normal phone usage.
Either card will give you a smooth experience.

493MB file copied from sdcard to eMMC in 90s = slow as f*** for some reason.

PC to eMMC transfer over usb:
493 MB file transfer from PC to eMMC in 54 seconds = ~9.13 MB/s

PC to sandisk over usb:
493MB file PC->ext4 partition (WV hack) in 31s = ~ 16 MB/s.
493MB PC->fat32 in 31s = ~16 MB/s
493MB fat32->PC in 31s = ~16 MB/s
493MB file ext4->PC in 37s = ~13.32 MB/s

PC to samsung evo over usb:
493MB PC->ext4 in 51s = ~9.6 MB/s write
493MB PC-> fat32 in 47s = ~10.5 MB/s write
493MB fat32 ->PC in 27s = ~18.25 MB/s read
493MB ext4 ->PC in 31s = ~16 MB/s read


Below, Samsung and sandisk were tested in PC usb2.0 card reader plugged into usb3 port. Crystaldiskmark test comparison between sandisk and samsung. Obviously the card reader is a huge bottleneck. Google will show that the sandisk has much faster speeds.

But one thing to note is that 4K r/w on the samsung beats the sandisk on the 100MB test, but in the 500MB test, the samsung random write slows down a lot while the sandisk maintains roughly the same performance.




Conclusion:
In the phone, the sandisk has much faster large file read/write than both the eMMC and EVO. I'm not sure if this means much in real world usage. Big apps?? The sandisk allows faster file transfers from PC to phone. Other than that, you likely won't notice a difference in daily usability.

The lowest price seen on this sandisk 32gb Extreme Plus was $17 around Black Friday.
Lowest price for 32gb samsung evo is $13.

For $4 more on sale, the sandisk has presumably better quality MLC memory, much faster speeds, and a lifetime warranty with free shipping both ways if you ever need to RMA.

The samsung has cheaper and slower and lower-life TLC memory, a 10 year warranty, and samsung doesn't cover the cost for you to ship a broken card to them when you RMA. Like other companies, they will ship a replacement for free though.

If you can get the sandisk for $17, it's a no-brainer. With up to 80 MB/s read and 50 MB/s write in sequential mode in non-phone applications, it's more than suitable for DSLR, gopro, camcorders, future phones with inevitable higher video recording demands, etc.
Faster-than-phone performance and lifetime warranty is just icing on the cake.

.

 

[WarrantyVoider]

Thanks, nice work! So if the SD reader in the phone still has more headroom to push data even faster, it gives us hope that SanDisk Extreme Pro and Samsung PRO and the next generation of cards can do better on this phone.

Normally faster cards (for sequential access) are used in cameras and video cams. Obviously, this phone's camera doesn't push enough pixels to need a fast card, but I wonder if faster cards would allow you to snap pictures faster.

Ext4 is slowly being replaced by other file systems. It's still a great performer in general, but I suspect its access patterns are not ideally suited for flash-ram-based storage. Specifically, in journaling mode, it basically requires two write operation (one for journal and one for data) for each write request. With allocation unit/erase block being quite large on high-capacity cards, chances of corruption for a bad write are also higher. I've been using f2fs on my phone. Its random writes are faster, but somehow the random reads are a lot slower and so far I can't figure out why.

Like I said in the other thread, Samsung EVO is able to keep quite a few allocation units open at once. Over 30 I think, while some cheap generic brands can only do a single digit. So roughly, 30+ open allocation units with 16MiB each on a 32GB card. Perhaps that explains why Samsung does better at higher queue depth and why it slows down in the 500MB test. On the other hand, SanDisk's consistent numbers probably suggest much faster memory cells like you said. It makes me curious about the pro line from each manufacturer, with faster MLC memory (in Samsung's case) or with even better micro-controllers (presumably, in SanDisk's case).

Thanks again for doing the tests and for providing the results. Very interesting and informative.

 

[catchingup]

I didn't know about f2fs, and I just googled it.

Sounds like it would be perfect for crappy sd cards. Too bad the factory rom doesn't support f2fs. I thought I could format the sd card /data partition to f2fs and copy a backup to it.
But the phone runs fine as it is.
The low random write of the eMMC seems to be all that is needed.

 

[WarrantyVoider]

F2FS can be built as an out-of-tree module and inserted as needed. That's how I've been using it with the unmodified stock kernel. But that's another topic entirely. I was hoping random read speed could be much improved, but the overhead of going over the external/SD interface might be a bottleneck. Fortunately, the phone seems to work just fine using a fast enough SD card as its primary storage, so putting all of /data on the SD is not trading performance for space like the old days.

 

[catchingup]

All of the f2fs tests I have seen have had a 10-20% performance hit, but something like 1000% write gain.

Is that what you are seeing? Despite that, is there a difference in feel in day to day use?

 

[WarrantyVoider]

I don't feel there's a big difference in normal use. But for full disclosure, I should say that since I started using F2FS, I've been using the phone more for testing and development. My usage pattern has been different. I haven't been using the same apps regularly to make an objective comparison between the two file systems.

The following tests were all done with the stock kernel/rom. Remember the numbers are for your amusement only. Without proper scientific methods and testing conditions, they don't necessarily prove anything.

A1 SD numbers with Samsung 32GB EVO:
I ran each test twice (in different order) to show potential variability.
For ext4, I use stride=erase block size, whatever effect it has, I haven't tested it separately
For f2fs, I use section size=erase block size, background gc=off, inline data, inline dentry, inline xattr, flush merge
- random:
13.53/0.46 ext4
13.82/0.64 ext4
9.34/0.98 f2fs
8.31/0.98 f2fs
- accurate:
32.14/14.46 ext4
33.88/16.11 ext4
31.53/18.85 f2fs
31.34/13.29 f2fs

Tests I did when I first got F2FS working, with 16GB class 6 Samsung, MB-MSAGB (only spare card I had at the time), with each file system in a different (possibly misaligned) partition on the same card, all with default parameters:
- A1 quick:
15.56/13.79 sd fat32
11.09/10.11 f2fs
14.37/10.97 ext4
41.66/10.52 internal emmc ext4
- A1 random:
10.77/1.72 sd fat32
7.81/0.72 f2fs
10.84/0.41 ext4
17.24/0.20 internal emmc ext4
- Antutu:
15538, 15586, 15831 f2fs (Storage I/O: 514, 487, 369)
14588, 15837 ext4 (Storage I/O: 704, 755)
15616 internal emmc (Storage I/O: 575)
- Quadrant:
4860, 5104 f2fs (I/O: 6841, 6610)
4604, 4950 ext4 (I/O: 6067, 6569)
4793 internal emmc (I/O: 5549)

The Antutu and Quadrant tests were done at that time to see if they reveal the effects on overall system performance. But I realized they were too dependent on CPU/GPU performance. I think on this phone (at least with stock), when the system runs hot (like after running some benchmarks), the CPU/GPU slows down. So the results aren't all that reliable. Then again, I don't have a lot of experience benchmarking with them or interpreting data from their results.