TechSpot

Rfi

By Mictlantecuhtli
Feb 15, 2002
Topic Status:
Not open for further replies.
  1. Has anyone experienced problems caused by RFI? I had this weird problem (I think it's because of RFI): When my IDE cable was not shielded, transfer rate was about 400kb/sec (UDMA/100). But when I wrapped the cable and hdd into those plastic shielding bags (non-conductive), the speed went back to 27 Mb/sec.
    The cable was included in my motherboard package and it works, I've checked it.
     
  2. ToRN

    ToRN TS Rookie Posts: 189

    mmm, seems interesting. Sure it is because of the RFI? How did you measure?
     
  3. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Topic Starter Posts: 4,916   +9

    I don't have anything to measure it with, but I figured it's because of that. I have no idea what else it could be. Or is it this hdd - Samsung Spinpoint SV4084H?
     
  4. Per Hansson

    Per Hansson TS Server Guru Posts: 1,930   +126 Staff Member

    Aren't IDE cables already shilded?
     
  5. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Topic Starter Posts: 4,916   +9

    Define "shielded". Every other wire is ground, AFAIK, but the whole cable itself isn't shielded.
     
  6. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Topic Starter Posts: 4,916   +9

    With additional shielding:
    Code:
    hdparm -tT /dev/hda
    
    /dev/hda:
     Timing buffer-cache reads:   128 MB in  0.53 seconds =241.51 MB/sec
     Timing buffered disk reads:  64 MB in  2.56 seconds = 25.00 MB/sec
    
    Without:
    Code:
    hdparm -tT /dev/hda
    
    /dev/hda:
     Timing buffer-cache reads:   128 MB in  0.53 seconds =241.51 MB/sec
     Timing buffered disk reads:  64 MB in 15.30 seconds =  4.18 MB/sec
    
    This time it didn't drop that much, but it's still very annoying.
     
  7. Per Hansson

    Per Hansson TS Server Guru Posts: 1,930   +126 Staff Member

    Hmm, that seems strange; The information read from the cache isn't affected but the one from the platters are

    That seem very wierd since it's the info going from the harddrives cache that goes at insanley high speeds (It could actually hit the ATA standard your HD supports I.E 100MB...)

    But when the data is read from the platters it takes an eterninty to get it moving...

    Strange indeed!

    But as long as it's working for you...
     
Topic Status:
Not open for further replies.


Add New Comment

TechSpot Members
Login or sign up for free,
it takes about 30 seconds.
You may also...


Get complete access to the TechSpot community. Join thousands of technology enthusiasts that contribute and share knowledge in our forum. Get a private inbox, upload your own photo gallery and more.