Hey, I just finished setting up my first unRAID server and I just started moving data from my desktop over gbit lan. While using TeraCopy, I noticed the write speeds to my parity protected array were almost stable at 60 MB/s. That's very acceptable, considering I don't have a cache drive. However, as soon as I closed my browser (Chrome) I noticed the copy speed drop almost immediately down to 40 MB/s. First thing I did was open the browser again, and it jumped back up to 60 MB/s. This happens every time I close it and open again. None of the copies on the server are corrupted, they all play fine (media files). Now, seeing as this is my first attempt at anything unRAID related, I don't know if this is some kind of sorcery or just normal behavior.. should I just let it continue or does this demonstrate a flaw in my setup?

 

Additional info: At the moment I only have two brand new 2TB 7200rpm Seagate's in the tower. I will have to add my other drives one at a time after copying data off them. CPU is AMD A8-3850, ASUS F1A75-M motherboard with 4GB 1333MHz DDR3. I'm copying from my i5 Haswell desktop that has Windows 8.1 x64.

 

This is how it looks with the browser open:

 

IMO it must be sorcery really

 

When you say that speed increases when you re-open Chrome, you mean just Chrome with empty (or some other) page... or only when you open unRaid webgui on Chrome?

Yes, just some random page. Doesn't matter if it's "about:blank", google or the unRAID webgui.

 

I finished my first round of copies and all the files are fine, so I'm going to go forward with the next round of copying. Even though I really don't know what to make of this wizardry.

Whoa, you got a cache drive.  You should get write speeds close to 100MS/sec!!!

 

I use and love TerraCopy but I have never really been convinced that it was optimized for high speed copies across networks.  I am also not sure that it does not simply use Windows subroutines for the actual copy.  And I am not about to delve into the coding to try and figure it out. 

 

If you want to use a copy program which is more optimized for raw copy speed with low overhead, try ImgBurn.  This thing was first written back in the days when cpu and hard disk speeds were so slow that a CD write would fail if a screen saver activated!  And yes, you can do straight file copies with it.  But the interface is not really user friendly in that mode.  (I personally would rather use TerraCopy even if it is a bit slower!)

 

EDIT: I also noted that you are copying to a mapped drive.  Try copying directly to a share by opening ""Network" on your desktop, select your unRAID server and navigate to the share position where you want to copy to. 

Thanks for your input Frank. I do have a cache in my signature, but I've not yet added it to the unRAID system (I'll do that when I finish copying my ~8TB of data).

 

After I added a 2nd data drive to the array and started copying, the behavior described in my OP stopped. The transfer rate has also dropped, from a stable 60MB/s to about 30MB/s (sometimes it drops to 15MB/s and sometimes goes to 45MB/s, is this erratic rate normal?)

 

On the next copy I will navigate straight to the share, instead of using the mapped drive.

Thanks for your input Frank. I do have a cache in my signature, but I've not yet added it to the unRAID system (I'll do that when I finish copying my ~8TB of data).

 

After I added a 2nd data drive to the array and started copying, the behavior described in my OP stopped. The transfer rate has also dropped, from a stable 60MB/s to about 30MB/s (sometimes it drops to 15MB/s and sometimes goes to 45MB/s, is this erratic rate normal?)

 

On the next copy I will navigate straight to the share, instead of using the mapped drive.

 

Without cache drive, my transfer rates start out fast like yours.  What I think is happening is that unRAID is using available ram to buffer data until it can be written to the drive array.  After the buffer is full, the transfer rate slows down (eventually) to the array writing rate. 

 

Another thing.  Recognize that there is a certain amount of file overhead that has to occur before and after actual data writing.  Files, file permissions and (possibly) directory entries have to created and all that information written to the drives.  With a few large files, that overhead is almost insignificant.  If you are writing a lot of small files, it becomes really significant.  The transfer rate that TerraCopy shows is only for the actual data and data transfer does not occur during file housekeeping.  Hence, you see wide variations in transfer speeds. 

Ah, I see. Thanks for your answers, they added to my very limited unRAID understanding.

 

I transferred a few files and kept a close eye on the transfer rate and after it finished I calculated the average to be about 30MB/s, just as I expected before I started. So now I don't have to be freaking out when I see the rate shoot up to 60MB/s and down to 10MB/s a few seconds later. 

After I added a 2nd data drive to the array and started copying, the behavior described in my OP stopped. The transfer rate has also dropped, from a stable 60MB/s to about 30MB/s (sometimes it drops to 15MB/s and sometimes goes to 45MB/s, is this erratic rate normal?)

 

On the next copy I will navigate straight to the share, instead of using the mapped drive.

 

i would expect this behaviour. if you dont have a parity drive installed its simply writing to the driver. if you DO then since there is only 1 data disk it simply mirrors disk1 to parity.