USB instalation bad write/read rates

Help and Support Raspberry Pi
1

Hi there!

Some days ago I decided to reinstall my Kodi setup, with some other services (Lidarr, Jackett and Transmission). Everything was working, but for some weird reason seems I corrupted my SD.

So I ordered another cheap SD card and an USB 3.0, thinking that setup would be harder to corrupt and I would get better performance. Since first moment I was feeling everything more slow, so once everything was installed again I tried to benchmark write/read rates based on this thread Usb install vs sdcard - #21 by Zappatron My results:
Write

root@osmc:/home/osmc# dd if=/dev/zero of=test bs=1M count=512 conv=fdatasync
512+0 records in
512+0 records out
536870912 bytes (537 MB, 512 MiB) copied, 71.0382 s, 7.6 MB/s

Read

root@osmc:/home/osmc# free && sync && echo 3 > /proc/sys/vm/drop_caches && free && dd if=test of=/dev/null bs=1M count=512
              total        used        free      shared  buff/cache   available
Mem:         764724      357744       34208        5144      372772      347464
Swap:             0           0           0
              total        used        free      shared  buff/cache   available
Mem:         764724      358300      299624        5144      106800      350924
Swap:             0           0           0
512+0 records in
512+0 records out
536870912 bytes (537 MB, 512 MiB) copied, 21.9898 s, 24.4 MB/s

In comparison with thread results (SD instalation, Raspberry 2), and thinking my instalation is on an USB 3.0 flash drive, I though I am getting a really bad results specially on write (7.6 MB/s to 12.7 MB/s).

Is this OK? Is there a way to move all my installation to and SD in order to give it a try?

My setup
Raspberry 3 (old, so I supposed is A version?)
USB Kingston DataTraveller 16 GB
Kingston SD card
An external HD Seagate (not powered by Raspi, external power)

Thank you in advance

2

mainly when dealing with usb installations is the powersupply if you got a shitty powersupply it all fails downward

got a rpi3b too getting really good read write speeds but i ditched the standard power supplies for multi-port adapter

dunno why you went with DD when hdparm is installed.

hdparm -Tt /dev/sda
 /dev/sda:
 Timing cached reads:   1412 MB in  2.00 seconds = 705.79 MB/sec
 Timing buffered disk reads:  98 MB in  3.02 seconds =  32.43 MB/sec
3

Thanks Toast!

dunno why you went with DD when hdparm is installed.

Cause I am not really know what I am doing :smile:

Here my metrics:

/dev/sda:
 Timing cached reads:     8 MB in  2.00 seconds =   4.00 MB/sec
 Timing buffered disk reads:  92 MB in  3.02 seconds =  30.44 MB/sec

Yeah, there is not a typo everything is taken forever…
I returned home right now, and seems Transmission has stopped. Not sure why. If I check status says Main PID: 465 (code=killed, signal=KILL)

Also said I have overclocked my raspi to Turbo (after my first message), just to see if that could help. But I think is going to be worse.

Can not check power adapter right now, but I think is 1 - 1.5 A . What value should be enough?

4

That’s not enough 5v 3A is highly recommend for RPI3b. I recommend not overclocking until your sure of your setup

This holds some valuable info

5

I checked it yesterday, and as you suggested its 5v 3A. I power everything off just to see that, remove overclock, and checked again the rates:

root@osmc:/home/osmc# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   962 MB in  2.00 seconds = 481.27 MB/sec
 Timing buffered disk reads:  72 MB in  3.05 seconds =  23.61 MB/sec

So much better!

Just returned today from work, and again bad rates:

root@osmc:/home/osmc# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:     2 MB in  6.36 seconds = 321.83 kB/sec
 Timing buffered disk reads:   2 MB in  5.78 seconds = 354.22 kB/sec

This is my topat that moment:

top
top715×368 89.4 KB

I installed iotop trying to see something more but nothing interesting… Again checked read rates and again good ones (without reboot this time).

So I have no clue what is going on here, any ideas? :thinking:

6

make sure to kill of transmission when your testing since it can be using the drive while testing.

7

Thank you very much for all your help Toast

Transmission just have one dead torrent and is pointing to my external HD, so I dont see so much relation…

On the other hand, I executed iotop and found this:

iotop
iotop720×416 39.1 KB

that jbd2 proccess its eating 40/50 % IO all the time. Searched for it on google and found some suggestions about set noatime on fstab. Went there and found the following:

/dev/mmcblk0p1  /boot    vfat     defaults,noatime,noauto,x-systemd.automount    0   0
# rootfs is not mounted in fstab as we do it via initramfs. Uncomment for remount (slower boot)
#/dev/sda1  /    ext4      defaults,noatime    0   0

So not sure if uncomment last line, as system is there and I am worried of breaking everything. Also, should I set a line for my external HD? At this moment I need to unplug each time I reboot the system.

Thank you

8

I think you’ll find that the IO> column is the percentage of time that the process is spending (ie usually waiting) on I/O.

See performance - How does iotop calculate the relative I/O activity? - Unix & Linux Stack Exchange

9

Seems you got a lot of stuff on your rpi, I tend to split up what a raspberry does if a raspberry is a mediacenter then its purpose is a mediacenter not a general downloader

many seem to crap as much as possible into a rpi thus overloading it.

would recommend setting up all that downloaders on a separate rpi, plus im not a fan of mono since its not native to Linux it tends to be a resource hog and kodi by itself can be quite a hungry beast