Dr0bac
Posts: 3
Joined: Sun Dec 03, 2017 11:21 pm

Samsung 32 gb EVO + poor performance

Sun Dec 03, 2017 11:29 pm

I bought 32gb samsung evo + after seeing few raspberry pi micro sd card speed tests, and my card is not performing very well..
can you tell me if i'm doing something wrong?
32gb evo + can theoretically gain 20 MB/s write and 95 MB/s read speeds, i know that i will not get these speeds..

First i put micro sd card in laptop sd card slot with windows os and ran few tests.. When i transfer big files from and to sd card i get around 20 MB/s write and 80 MB/s read speeds..when i transfer 100+ photos i get 10+ MB/s write speed.. Then i ran CrystalDiskMark and i also got around 20 MB/s write and 80 MB/s read speeds, and sequential speed around 7 MB/s read and 1 MB/s write..
On fresh Raspbian install i ran these tests that contain hdparm, dd, and iozone..

curl http://www.nmacleod.com/public/sdbench.sh | sudo bash
curl https://raw.githubusercontent.com/geerl ... chmarks.sh | sudo bash

and when i saw poor performance i tried to overclock sd card with dtparam=sd_overclock=100 line in boot/config.txt and performance was little better but far from raspberry pi micro sd card tests i saw on the net..
i get 0.7 MB/s random write in iozone, in tests on the net people are getting 3.0 MB/s speeds with that micro sd card..
i ran tests in 3 rounds to be sure, these are screenshots of my tests in imgur album bellow

https://imgur.com/a/fyx2h

If you have some suggestions, please share.. Thanks

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HawaiianPi
Posts: 3027
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Location: Aloha, Oregon USA

Re: Samsung 32 gb EVO + poor performance

Mon Dec 04, 2017 7:10 am

Random I/O performance is the bane of all SD cards and cheap USB flash drives. That's what makes them a poor choice for an OS drive (much of what computers do is non-sequential). However, as poor as the EVO+ random performance seems to be, it's still far better than most other SD cards (which are typically sub-MB/s level). I have some "fast" USB flash drives that clock well over 300/200MB/s read/write sequential, but single digit (<10MB/s) random reads and <1MB/s for random writes.

Code: Select all

   Sequential Read (Q= 32,T= 1) :   320.953 MB/s
  Sequential Write (Q= 32,T= 1) :   255.359 MB/s
  Random Read 4KiB (Q= 32,T= 1) :     6.216 MB/s [  1517.6 IOPS]
 Random Write 4KiB (Q= 32,T= 1) :     0.026 MB/s [     6.3 IOPS]
         Sequential Read (T= 1) :   359.652 MB/s
        Sequential Write (T= 1) :   192.774 MB/s
   Random Read 4KiB (Q= 1,T= 1) :     5.512 MB/s [  1345.7 IOPS]
  Random Write 4KiB (Q= 1,T= 1) :     0.010 MB/s [     2.4 IOPS]

  Test : 1024 MiB [G: 63.5% (74.9/118.0 GiB)] (x5)  [Interval=5 sec]
  Date : 2016/06/05 3:16:32
    OS : Windows 10  [10.0 Build 10586] (x64)
If you want better, use an SSD drive.
Image
Heck, even a hard drive will outperform an SD card or USB flash drive on random I/O.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

hommar
Posts: 154
Joined: Sat Mar 25, 2017 1:55 pm
Location: Russia, Yekaterinburg

Re: Samsung 32 gb EVO + poor performance

Mon Dec 04, 2017 5:42 pm

You can change FS to f2fs for more perfomance

Rascas
Posts: 448
Joined: Tue Mar 11, 2014 6:18 pm
Location: Porto, Portugal
Contact: Website

Re: Samsung 32 gb EVO + poor performance

Mon Dec 04, 2017 6:09 pm

The thing is, the first revisions of Samsung EVO+, and also EVO (normal orange one) had good speeds, +/- like the ones in that benchmark, but the newer revisions of that sdcards, perform a lot worse on the Raspberry Pi. I have 1 EVO+ and 1 EVO with about the same scores, but the last ones that I tested (newer ones) perform much worse, like yours. I cannot explain why but I think this has to do how Samsung produces them now, probably they are more optimized for UHS (which the PI doesn't support) and have worse performance on non UHS mode. In the latest ones I cannot even get the Pi to work properly with them, if I do some intensive writes on them they became really slow, sometimes it even feels like the system freezed and if I reboot, the system has corrupted files or doesn't even start.
But they still work fine on a laptop or a smartphone, if they support UHS, with +/- the announced speeds.
I noticed somewhat a close behaviour with other brands, like Sandisk Ultra microSD cards, which always have performed quite well but the newer ones also have worse performance but atleast they don't break the system.
If you really want to stay with microsd cards, newer ones, my recommendation is to choose a fast one (don't forget that 4k reads/writes are the most important on the PI) but not a UHS-1 one which is quite difficult nowadays.

Dr0bac
Posts: 3
Joined: Sun Dec 03, 2017 11:21 pm

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 12:48 am

Thanks for explaining..it's sad that after few days of searching for a perfect sd card i ended with poor one..but well, that's life..
I also have 1 tb wd elements external hdd, maybe i will install os there..but i'm worrying that when os is on hdd, that hdd will never go to sleep, or very little..

Rascas
Posts: 448
Joined: Tue Mar 11, 2014 6:18 pm
Location: Porto, Portugal
Contact: Website

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 1:55 am

@HawaiianPi just for coriosity, can you run iozone on the Pi with that ssd and post the results please ?

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bensimmo
Posts: 3457
Joined: Sun Dec 28, 2014 3:02 pm
Location: East Yorkshire

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 7:58 am

Out of curiousity are they the "+" or the "Plus" ?

Dr0bac
Posts: 3
Joined: Sun Dec 03, 2017 11:21 pm

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 3:39 pm

Plus is written on the card and on the package
Image

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bensimmo
Posts: 3457
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Location: East Yorkshire

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 3:42 pm

Dr0bac wrote:
Tue Dec 05, 2017 3:39 pm
Plus is written on the card and on the package
Image
These are newer and different to the "+"
So would be a different benchmark you would need to comapare to. EVO+ is not equal to EVO Plus

uhclem
Posts: 2
Joined: Mon Sep 18, 2017 7:54 am
Location: NH, USA

Re: Samsung 32 gb EVO + poor performance

Tue Dec 05, 2017 8:44 pm

HawaiianPi wrote:
Mon Dec 04, 2017 7:10 am
...
Heck, even a hard drive will outperform an SD card or USB flash drive on random I/O.
That's pretty ludicrous. Think about it ... average latency alone for a 7200rpm HDD is 4ms. Then, add even a little seek time, and ...
E.g., a HGST 4TB 7200rpm drive, connected @ Sata2, does 600 KB/s with 4KB random reads, drastically short-stroked to a 32GB range [but, only 275KB/s over full 4TB range].

In contrast, even @ USB2 (on a Pi3, using cheap USB2 reader), a 32GB uSD does 4.5 MB/s (Lexar 633x,Class10,U1) and 6 MB/s (Sandisk Extreme U3). On the Pi3 built-in uSD, with dtparam=sd_overclock=100, the Sandisk Extreme 32GB does 7.2 MB/s.

--uhclem

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