maplevshoney

Q: AC Wireless Read/Write Speeds Slow (and Different)

Hello All,

 

I just purchased a new Mac Mini and unfortunately it is too far from my media server to run an ethernet cable (I just moved) so I'm using an Airport Extreme (new model with AC protocol).  But the read speeds seem to be slow as I cannot stream some high bandwidth movies off the server.  I've tested the transfer speeds and it appears that I am getting the following:

 

READ: 24 MB/s (or 192 Mb/s)

WRITE: 8 MB/s (or 64 Mb/s)

 

Can anyone explain to me why these speeds are not the same?  And shouldn't they be much faster?  I'm getting a full signal and I've attached the technical details if that helps explain anything. I would love to know what speeds you guys are getting with your Airport Extreme.

 

Thanks!

 

Screen Shot 2016-03-30 at 10.04.08 PM.jpg

Mac mini, OS X El Capitan (10.11.4)

Posted on Mar 30, 2016 10:08 PM

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Q: AC Wireless Read/Write Speeds Slow (and Different)

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  • Helpful answers

  • by ckuan,

    ckuan ckuan Mar 30, 2016 10:16 PM in response to maplevshoney
    Level 7 (33,190 points)
    Mar 30, 2016 10:16 PM in response to maplevshoney

    How far away is your Mac to your server?

    Are there walls or something else in the line of sight?

    Have you tried the 2.4 GHz connection instead?

  • by Tesserax,Helpful

    Tesserax Tesserax Apr 2, 2016 12:06 PM in response to maplevshoney
    Level 9 (53,940 points)
    Wireless
    Apr 2, 2016 12:06 PM in response to maplevshoney

    First read speeds will typically be faster than write with just about any hard drive. Regardless if it is locally attached or remote.

     

    Let's take a look at the wireless numbers you provided:

    • Security: WPA2 Personal - This is not only the most secure method available today, it is also the most efficient performance-wise ... so no problem here.
    • Channel: 149 (5 GHz, 80 MHz) & PHY Mode: 802.11ac - Your Mac mini is connected to the AirPort Extreme with the 802.11ac mode. Also good.
    • RSSI: -79 dBm & Noise: -92 dBm - You would use both of these values to calculate the Signal-to-Noise Ratio (SNR). This is one indicator of the "quality" of the wireless connection. You want this value to be 25+ dB. Doing the math: -79 - (-92) = 13. This would indicate poor signal quality.
    • Tx Rate: 117 Mbps - This indicates the maximum bandwidth available with the current wireless connection. As you know, 802.11ac is much more capable than that.
    • MCS Index: 3 - This is a measure that defines the theoretical throughput for a single spatial stream in Mbps. An MCS value of 3 would provide a maximum throughput of 117 Mbps. This matches the TX Rate that you got.

     

    Ok, with all that said, I believe the issue of your poor read/write speeds is directly related to the quality (or lack thereof) of the wireless signal between your Mac mini and the AirPort base station.

     

    Please take a look at the following AirPort User tip for some disk access performance comparisons.

  • by maplevshoney,

    maplevshoney maplevshoney Apr 2, 2016 12:10 PM in response to Tesserax
    Level 1 (13 points)
    Mac OS X
    Apr 2, 2016 12:10 PM in response to Tesserax

    Hey Tesserax thanks for the information.  I believe you are correct as the Mac mini is in a credenza in my living room separated by two walls and a short hallway from the Airport Extreme.  Seems obvious that the signal would degrade but I am being misled by the fact that the Airport icon is showing full bars.  If the signal has been compromised as such, why does it show a full signal in the icon?

     

    That said, would the purchase of another Extreme AC router set to bridge mode help the situation, if I placed it between the two points? 


    How about if I placed it into the credenza next to the mini with an ethernet cable?  Would the same degradation be a problem or would the extremes communicate to each other better than the extreme/mini?

     

    Thanks!

  • by Tesserax,Solvedanswer

    Tesserax Tesserax Apr 2, 2016 5:34 PM in response to maplevshoney
    Level 9 (53,940 points)
    Wireless
    Apr 2, 2016 5:34 PM in response to maplevshoney

    If the signal has been compromised as such, why does it show a full signal in the icon?

    Unfortunately, the icon is not very reliable, not much else I can say about that. I don't use it myself and rely on the numbers in the pop-up window.

    That said, would the purchase of another Extreme AC router set to bridge mode help the situation, if I placed it between the two points?

    Potentially, yes ... but, I would strongly recommend either taking the Mac mini out of the credenza or use a wired connection for it instead. Also, understand, that although you will, most likely, improve the signal strength by extending the network with another base station, your extended network will take an overall bandwidth "hit." Meaning, you may still not get the data rate you are looking for this way to be worth the cost. However, unless you try it, you won't actually know. Besides Apple does offer a return policy if it doesn't work out.

    How about if I placed it into the credenza next to the mini with an ethernet cable?  Would the same degradation be a problem or would the extremes communicate to each other better than the extreme/mini?

    Yes, the extending Extreme would "see" the same poor signal that your Mac mini sees. No gain in doing this. Your thought to place one in-between would be a better one. Going with this option, the placement of that Extreme will be critical. Please check out this AirPort User tip for more details.

     

    You may also find that simply making slight placement changes for either the mini or the Extreme or both may solve the problem without having to get another base station.

  • by maplevshoney,

    maplevshoney maplevshoney Apr 2, 2016 5:37 PM in response to Tesserax
    Level 1 (13 points)
    Mac OS X
    Apr 2, 2016 5:37 PM in response to Tesserax

    Thank you, I have a better understanding of the mechanics here now. You have been very helpful

  • by ckuan,

    ckuan ckuan Apr 2, 2016 5:46 PM in response to maplevshoney
    Level 7 (33,190 points)
    Apr 2, 2016 5:46 PM in response to maplevshoney

    I would still suggest you test the 2.4 GHz connection (802.11 n).

    It's better through walls then using 5GHz ac.