Let this be a lesson to all!!

[Old Sparky]

Needing to check the make & model of a temporarily added HDD a short while ago, I unplugged the device from a SATA/IDE adapter whilst the PC was switched on and running!  When I tried to continue use, there was no cursor, only a short vertical line and a 'frozen' screen.  I had to reboot the machine twice to restore normal operation.  With my background in radio & electronics I should know better!   No doubt a spike or pulse shut down some function, but all appears to be OK now, thank goodness!

[Keithstv]

Theoretically a SATA drive can be removed without powering down as the connectors are designed to make all the ground connections first with pre-charge connections for the power connections. However this may now allow disconnection if any form of adaptor is used.

I have connected and disconnected probably hundreds of SATA drives at work without always powering down without problem.

Keith

[Old Sparky]

This evening, when I switched on the computer, 'disc error' message appeared, and I had to reboot it before I could log in and access my desktop, etc. Until earlier today, I don't recall this happening at all before.

[Nick]

Unplugging a storage device before dismounting it on pretty much any operating system, including Windows, is a BAD PLAN.

As rotating (as opposed to solid-state) disks are inherently slow devices, operating systems tend to use a "write back" cache - when you write data to a disk, its actually written to a bit of memory and the user programme gets immediate confirmation of the write being complete...

...however, the data is actually in volatile memory - the operating system writes the data to physical disk in the background whilst the user programme goes on its way...

The big upside of this approach is that write I/O intensive applications run very fast.

The BIG downside is that if the power fails (and there is no UPS) or the DISK IS REMOVED UNEXPECTEDLY (!!) then that data is essentially lost and the disk will possibly become corrupt.

You should check your disk structure & repair it if necessary as soon as is possible.

It is possible to change the cache type to "write though", where the user application has to wait until the data is physically written to disk, but that will make most applications that write to files run very slow - note that these setting are on a SYSTEM, not application level, i.e. you change the settings, it effects everyone and everything.

Note that there are at least two types of disk corruption: Corruption of the file system data structures, i.e. directories/folders etc. and then there's file corruption where the contents of a file which has an internal stucture, e.g. an Outlook PST file, becomes corrupt.

The first type of corruption can be fixed by chkdsk and other similar utilities; the second is more subtle as its application dependent, so you need a tool related to that application to fix it, e.g. Outlook has SCANPST.EXE to repair the internal structure of PST files.

Never, ever, remove a running storage device - if you do so, all bets are off. You may be lucky, but generally something subtle and nasty happens that may only manifest itself later, generally when you really really don't need it to

[Old Sparky]

As I said, Nick, 'wise with hindsight'. Thankfully this computer has been running OK since last Friday, though there are occasionally 'blips' when, e.g. sections of a page are moved right or left of where they should be. Haven't tried to run the HDD I removed again, yet, though, but the data on it had already been saved to a memory stick, so no real harm done. I now have a replacement tower so will be setting that up soon in any case.

[Joe]

e.g. sections of a page are moved right or left of where they should be.  

If that's in Chrome, I've having that problem on ALL my computers since an update last week.

— Joe

[Old Sparky]

This was in Chrome, Joe. Having just connected up the PC I got from unreal dave, I'm, for the moment using I.E. 11, and am not having the problem. I'm undecided whether to stay with I.E., go back to Chrome, or to Firefox, which I was using up to about 6 weeks ago.