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If one of the other experts knows what the cause of the issue that will be great, as the method I'd use is a bit tedious.<br />
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Download a copy of <a href="https://technet.microsoft.com/en-us/sysinternals/bb896645" rel="ugc">Microsoft Process Monitor</a>.<br />
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Set it to monitor as shown below.<br />
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Let it run for a minute or so (assuming that the issue is occurring every few seconds, a minute should be long enough).<br />
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Then examine the captured events for something that happens at the same rate as the disk issue.<br />
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<i>Side note</i>: &nbsp;There is also a spin-down time that is settable in most external drives' firmware, but it doesn't sound like that is the issue here. &nbsp;I'd investigate that only if other methods don't work out.<br />
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<a href="https://filedb.experts-exchange.com/incoming/2016/10_w42/1121499/new-1.gif" target="_blank" title="Process Monitor (27 KB)"><img alt="Process Monitor" class="file-block lazyload" style="max-width: 597px;" data-src="https://filedb.experts-exchange.com/incoming/2016/10_w42/1121499/new-1.gif" /></a>
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new-1.gif

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Thanks for the reply Dr Klahn - <br />
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It's coming up with &quot;INVALID PARAMETER Control: FSCTL_IS_VOLUME_MOUNTED&quot;. &nbsp;It's giving the same message for another virtual drive (Macrium Reflect), but i have no problem with that one. &nbsp;Do you know how I determine what the invalid parameter is? (and how to fix it)
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Is there an antivirus installed in the system? &nbsp;If so, which one?
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Very probable reason: it does not get enough power. <br />
Is it a USB-powered device or does it have a separate power supply? Please try other USB ports and, connect the power supply if you didn't do that already.
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Try disabling it, and see if the problem persists. &nbsp;Some antiviruses hook into all sorts of things in the system that they should not be touching.
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@McKnife - It is USB powered, but i have two identical WD drives, and I have no problem with the other one.
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So, then please for a test, exchange the drives, I mean, leave the usb cable of the working drive plugged into your computer and disconnect it from your working drive and connect it to the on-off-drive.
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@Dr Klahn - I have already excluded that drive from scanning and shield protection.
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@McKnife - It's still giving the same problem, so must be somewhere else. &nbsp;As i said in the original question, it's only started happening since I upgraded from W7 to W10
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OOOPS - my last comment didn't save. &nbsp;I really appreciate all the replies. &nbsp;I went next door and borrowed their computer, and my external hd worked fine. &nbsp;i made a copy of everything onto a memory stick, so now i can use the data fdrom my own computer.<br />
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I'm not 100% convinced that drive is faulty, but I will purchase a new one anyway.
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<div class="content wysiwyg-content">
Ever since upgrading to W10 my external drive keeps switching on and off every few seconds. &nbsp;I always have to disconnect it unless I need to use the data on it, and then it takes ages to get at the data because it switches out just as I am selecting files.<br />
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I cannot figure out why the system is accessing that drive as it only contains backup data. &nbsp;I thought it may have been something to do with indexing, but I have disabled that.<br />
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Any ideas as to what to try next?
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Ever since upgrading to W10 my external drive keeps switching on and off every few seconds.  I always have to disconnect it unless I need to use the data on it, and then it takes ages to get at the data because it switches out just as I am selecting files.

I cannot figure out why the system is accessing that drive as it only contains backup data.  I thought it may have been something to do with indexing, but I have disabled that.

Any ideas as to what to try next?

External drive keeps switching on and off under W10

Storage devices include any device used for storing and retrieving digital information. Hard disk drives (HDDs) use one or more rigid ("hard") rapidly rotating disks (platters) coated with magnetic material. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. The primary competing technology for secondary storage is flash memory in the form of solid-state drives (SSDs), but HDDs remain the dominant medium for secondary storage due to advantages in price per bit and per-device recording capacity. CD-RW (Compact Disc-ReWritable) is a digital optical disc storage format that allows information to be stored outside the mechanical HDD.

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Storage

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