Fusion Drive Start/stops

Suffa

macrumors member
Original poster
May 11, 2013
86
4
I've come across something strange. When I download something with utorrent, it first downloads at full speed, but quick after the speed goes down to 0 and I can see that the SSD is reading something at 30 MBps, and then it starts with full speed again for a couple of seconds before it stops again.

What can the problem be? Isn't fusion drive able to keep up?
 

chrfr

macrumors G3
Jul 11, 2009
8,401
2,638
I can see that the SSD is reading something at 30 MBps, and then it starts with full speed again for a couple of seconds before it stops again.

What can the problem be? Isn't fusion drive able to keep up?
That's not the fusion drive. Any regular disk can keep up with internet bandwidth.
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
I wonder what the problem is then. Seems like the SSD is moving data to the HDD and thats why the writing stops during transfer. Weird.
 

gnasher729

macrumors P6
Nov 25, 2005
16,574
3,153
I wonder what the problem is then. Seems like the SSD is moving data to the HDD and thats why the writing stops during transfer. Weird.
The opposite. Your download stalls for a bit, so the fusion drive says "this is a good opportunity to copy some stuff to the hard drive while I'm not busy".
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
But it doesnt look like it stalls, it goes full speed, and then down to 0, and when it does that i can see that the SSD is reading/writing data, and when that is done, the download goes full speed again..
 

Bear

macrumors G3
Jul 23, 2002
8,089
4
Sol III - Terra
But it doesnt look like it stalls, it goes full speed, and then down to 0, and when it does that i can see that the SSD is reading/writing data, and when that is done, the download goes full speed again..
Try a large direct download from somewhere if you really want to test. Torrents have so many factors affecting performance, it's difficult to say where the issue is.
 

Nuke61

macrumors 6502
Jan 18, 2013
325
0
Columbia, SC
But it doesnt look like it stalls, it goes full speed, and then down to 0, and when it does that i can see that the SSD is reading/writing data, and when that is done, the download goes full speed again..
A SLOW HDD can transfer data at ~100 megaBYTES per second. A FAST home internet connection can transfer data at 100 mega BITS per second, or roughly, 1/10th as fast. As has been said before, the Fusion drive is not the issue, it's your internet connection.
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
No its not the connection, its not a problem when using windows.

So its just a big coincidence that the fusion drive starts working with something as the speed go down, and when it stops the download continues?
 

AppleFan360

macrumors 68020
Jan 26, 2008
2,196
677
Does this happen on other downloads (non-torrent)? It's highly doubtful the Fusion drive is causing this problem. The internet in general isn't perfect. Torrents are especially unpredictable.
 

Nuke61

macrumors 6502
Jan 18, 2013
325
0
Columbia, SC
No its not the connection, its not a problem when using windows.
My guess is the OS X torrent client is having issues.

So its just a big coincidence that the fusion drive starts working with something as the speed go down, and when it stops the download continues?
Since even an older/slower HDD is easily 10 times faster than a normal (U.S.) internet connection, I just don't see the Fusion drive being the issue.

Point the torrent download to an external HDD or even a USB flash drive. At least that way you can prove one way or the other that it's related to the Fusion drive.
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
I just think it's weird that as soon as the SSD starts reading at 30 MB/s, all downloads stop. And when it stops reading, the download continues.

http://i177.photobucket.com/albums/w236/fredio/Skaumlrmavbild2013-06-13kl113428_zps05668329.png

Seems like the fusion drive is doing something, and can't write data until it's done. But i dont understand what it is doing, if it was moving files, it would be writing data, now its just reading, nothing else and no activity on the HDD.
 
Last edited:

chrfr

macrumors G3
Jul 11, 2009
8,401
2,638
I just think it's weird that as soon as the SSD starts reading at 30 MB/s, all downloads stop. And when it stops reading, the download continues.

http://i177.photobucket.com/albums/w236/fredio/Skaumlrmavbild2013-06-13kl113428_zps05668329.png

Seems like the fusion drive is doing something, and can't write data until it's done. But i dont understand what it is doing, if it was moving files, it would be writing data, now its just reading, nothing else and no activity on the HDD.
If you have only 79GB on your Fusion drive, ALL of your data resides on the SSD, so there is no file moving going on.
What app shows the information in your screen capture?
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
I dont think the program is showing incorrect information, it does everything else perfectly.

It's iStat Menus 4
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
Do you think it's bad to use utorrent with Fusion Drive? Or shouldn't that be a problem?
 

Nuke61

macrumors 6502
Jan 18, 2013
325
0
Columbia, SC
Do you think it's bad to use utorrent with Fusion Drive? Or shouldn't that be a problem?
Unless your machine is broken, Fusion isn't the issue. Once again, have you tried the option of telling uTorrent to download to an external drive? Tell it to download to a flash drive, or even an external hard drive. See if the problem continues when you download to something OTHER than the Fusion drive. It's basic problem solving... if uTorrent has no problem downloading to a drive other than your Fusion drive, your Fusion drive has a problem with it. If uTorrent does the same thing (start/stop) then it's a uTorrent problem.
 

torana355

macrumors 68040
Dec 8, 2009
3,419
2,299
Sydney, Australia
Do you think it's bad to use utorrent with Fusion Drive? Or shouldn't that be a problem?
I use uTorrent with the fusion drive in my iMac and i have no such issue. I use a private tracker so my speeds are stable (i leave utorrent on 24/7) and very very fast :) The issue would be the utorrent setup or the tracker you are using.
 

gnasher729

macrumors P6
Nov 25, 2005
16,574
3,153
Is it ok to torrent on a SSD? Isn't that very damaging?
You may make sure that you don't try do download illegal copies of Mac software, because that's the surest way of getting a trojan that messes your Mac up. And there are plenty of torrents for downloading illegal copies of music / videos / books etc., which is very damaging to the artists and may be damaging to you if you are caught.

But what makes you think that using an SSD drive would make any difference?

Nuke61 gave you the basic options of problem solving - if A and B together causes a problem, try to change either A or B and see if the problem stays or goes away.
 

Suffa

macrumors member
Original poster
May 11, 2013
86
4
Yea im not here to talk about downloading copyrighted content. Torrenting is not only for illegal downloads.

And since your answer is like that you probably have no clue what you're talking about.
 

Nishi100

macrumors 6502a
Mar 27, 2010
867
0
Is it ok to torrent on a SSD? Isn't that very damaging?
Are you talking about the write limit on an SSD being smaller than that on a traditional hard drive?
If you are then there's little to worry about. It is true that SSD's have a more limited write limit, if you torrent normally (20-40GB a month), the other components of your computer will most likely go before your SSD does; heck your HD will probably go before your SSD. Just remember to backup daily.

Normal consumers like you or I don't need to worry about SSD write limits, it's mainly large companies with stacks of SSDs using them 24 / 7 writing loads and loads of small files to the SSD.

If you're torrenting 15-20GB a day, then it might be better practice to save it to a traditional hard drive then copy the whole file over when it's done.