[coolbelief]

My 16GB N9 while in Mass Storage Mode goes as fast as 3MB/s (Writing on avg) no matter if its one big file or multiple small files however it gives back the same file on different partition on HDD at 21MB/s (Reading on avg).

Copying a 866MB file TO N9:

Getting the same file back to a different partition on HDD:

Not a huge problem for me but I'm interested to know if its normal, can anyone with 16GB model check this for me please?

PS. Tried all USB ports available on my laptop.

[grschinon]

It's perfectly normal. Writing to NAND flash memory is always slower than reading back from it.

[coolbelief]

Thanks grschinon for reply, I'm actually not concerned about the difference between Read/Write speed as you said that's perfectly normal but Write speed doesn't seem right to me. Did a little bit of research and I came to this post http://shootspeak.com/2011/10/09/nokia-n9-performance-test-roundup/  it mentions that for 64GB model avg write speed is 20MB/s and a *guess* for 16GB model ~14MB/s write on avg. I'm not getting even half of that, couple of dirt cheap SD cards I've perform better than 3MB/s.

Tried it on another Win7 PC with same results.

[jaripi]

yes, it should be better ... I just copied avi file to my N9 ... from Windows 7 32-bit ... write 14,5 - 15,5 Mb / s. (it is nice, good enough for me) and I checked read too, 22,5 - 25,5 Mb / s.

[coolbelief]

@jaripi thanks for testing, just for confirmation your N9 is 16GB version right?

[jaripi]

yes, it is ... N9 16 Gb black ...

[coolbelief]

Well that confirms my doubt, there is problem somewhere and don't think it's my laptop as the second pc I tried gave the same result. Might try it on Linux and if it doesn't improve there too then the problem sure is with my N9.

Thanks once again jaripi

[cpitchford]

It would be interesting to see the kernel log afterwards. Not that I'm a big win7 user, but I wonder if something else is hammering the device at the same time (perhaps indexing content? would be a bit retarded)

You could try a linux OS (maybe one that boots from USB) to see if it improved.. If not, the kernel log from the linux on your PC would be interesting and probably very telling..

[coolbelief]

Thanks for advice CP, not had enough time to sit and play with it today! First thing to-do tomorrow morning

[coolbelief]

Tried Mint 11 live usb, unfortunately same result. I've attached kern.log file below. Please note this was taken from live system after I finished my testing. Looked upon it but couldn't find anything "telling" and that tells how advance I'm with Linux 

[algis87]

I also have this problem. Writing speed is only 3MB/s on mass storage mode. However, when I choose sync & connect option the speed is normal. I copied a 700 Mb file in about a minute, which is ~11.5 MB/s

[slipkornsaad]

that's not normal mainly after watching this demo http://www.youtube.com/watch?v=feAUpH7_MAU what's your system set?

[coolbelief]

Some progress!

Did the reset (Clear device) but it didn't turned itself back "on" afterwards which I think it should after a successful reset. Anyway back to the topic, tested USB speed, same result!!

Formatted the disk volume while mounted in Windows and it worked, 14 MB/s avg. Still not sure what was the reason and I'm afraid if I "Reset" it once more for testing purpose it'll be problematic again.

Edit: Please remember to backup your data before formatting the drive if you have similar problem.

[cpitchford]

When using Mass storage mode, only part of the internal storage is connected to the PC via USB. Essentially only one partition is made available. The phone keeps applications and user data on the other partitions..

When the mass storage is connected to the PC it is detached from the phone. The phone can't access this large data partition at the same time. BUT what if something had failed on the phone.. and for some reason it is trying to access something continuously.. generating IO traffic to the mass storage..

Even though the phone and the PC can't access the same data at the same time, they ARE sharing the same physical hardware (emmc flash)

So, if the phone is upset that the data volume is unavailable, what if it generates "unhelpful" IO traffic that slows down the flash for the PC?

Trying to read AND write to a flash device at the same time will give you a lower through put than reading or writing alone.. So, the phone maybe reading through some data that is interrupting the write process giving you a lower through put.

Long and short, it'd be hard to prove without it happening again.. But I'd be interested to see the output of iostat, top or hdparm -t on the N9 if it happens again..

There are tools to see what processes are doing what, I think they're available as installs under the developer mode list