[Webinar] Streamline your web hosting managementRegister Today

x
?
Solved

True transfer rate?

Posted on 2013-01-13
4
Medium Priority
?
739 Views
Last Modified: 2013-01-13
I have a Macbook Pro with an SSD and an external Firewire 800 7200RPM drive.  I cloned 210GB of data from the MBP to the ext drive.  It took 1 hour and 10 minutes.  

Firewire 800 transfers at 780Mbs, which translates to 5820MB per hour or 582GB per hour.  I got less than 1/2 of that in an hour.  The 7200RPM drive and SSD factor in.  How do I get some idea on how fast the actual transfer rate was?
0
Comment
Question by:brettr
4 Comments
 
LVL 84

Assisted Solution

by:Dave Baldwin
Dave Baldwin earned 600 total points
ID: 38772418
With variable size files, it is difficult to get a better estimate.  The extra time is taken up by the disk, file, and directory overhead and some network overhead.  Before each file or directory can be transferred it has to be created on the destination.  For that reason, transferring one large file will seem to go quicker than transferring the same amount of data in a lot of small files.
0
 
LVL 31

Accepted Solution

by:
Frosty555 earned 800 total points
ID: 38772556
Your real-world transfer speed worked out to be:

210GB * 1024 / 70 minutes / 60 seconds = 51.2 Megabytes per second.

Firewire-800 has a theoretical maximum bandwidth of 800MBPS. Theoretically the fastest transfer speed possible on this interface is:

800MBPS / 8 = 100 Megabytes per second.

However, this is just the raw speed of the wire, you have to take a lot of other things into account:

     - Communication protocol overhead
     - Network overhead
     - Application level overhead (reading the data on the SSD, processing it etc)
     - Capabilities of the receiving device (it's a 7200rpm disk. There is latency, overhead and limitations when writing to that physical device)

My guess is the bottleneck was the disk speed of your external firewire hard drive, and 51.2 Megabytes per second is probably quite reasonable.
0
 
LVL 70

Assisted Solution

by:Gary Case
Gary Case earned 600 total points
ID: 38772618
"...  How do I get some idea on how fast the actual transfer rate was? "  ==>   You just did exactly that.    You transferred a known amount of data in a known amount of time -- so you just do the math (as frosty did above) ==> in your case the rate is 51.2 MB/s.

Note that a modern 7200 rpm drive easily exceeds that rate, even on the slower inner cylinders (and will double it on the outer cylinders), so it's not likely your drive caused any slowdown UNLESS you were transferring a lot of relatively small files.

If you want to be sure the drive performance isn't a notable factor, create a single very large file (100MB or more);  then measure the time to copy that.
0
 

Author Comment

by:brettr
ID: 38772629
There are small files involved with the transfer and many folders must be created.  I can't say how many but assume lots.  That is probably the source of the slow down.  Thanks.
0

Featured Post

[Webinar] Kill tickets & tabs using PowerShell

Are you tired of cycling through the same browser tabs everyday to close the same repetitive tickets? In this webinar JumpCloud will show how you can leverage RESTful APIs to build your own PowerShell modules to kill tickets & tabs using the PowerShell command Invoke-RestMethod.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

New style of hardware planning for Microsoft Exchange server.
For years I have put up with a wireless mouse that consistently disappears or is non-responsive.  This is the story of how I discovered it wasn't really the mouse!
This Micro Tutorial will teach you how to reformat your flash drive. Sometimes your flash drive may have issues carrying files so this will completely restore it to manufacturing settings. Make sure to backup all files before reformatting. This w…
How to fix display issue, screen flickering issue when I plug in power cord to the machine. Before I start explaining the solution lets check out once the issue how it looks like after I connect the power cord. most of you also have faced this…
Suggested Courses
Course of the Month10 days, 7 hours left to enroll

591 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question