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When I use Windows Explorer to copy 100 gigs or so, the PC slows down and becomes a lot less responsive for the hour or so it takes. Task Manager confirms that there's no single task responsible for this (97% of the CPU is allocated to System Idle Process); even Explorer isn't showing much CPU allocation.
The machine is perfectly responsive when this copy is not taking place; indeed, it performs better when I'm running a VM on it then when I've shut down the VM and am copying its files!
Is there some way of having windows treat the task of copying the files as much less deserving of my PC's resources than whatever I'm doing? I don't mind making the file copy take 50 times as long as it would otherwise take. I'm just moving backups around, from C: to D: which are both partitions on the same physical disk.
This is on a HP desktop PC: i7, 64 bit, 16 gigs of ram, 8 cores at 3.4ghz, Windows 7 SP1.
1Your storage is too slow. There is nothing you can do about this. Unfortunately, Windows 7 still has the old-style Task Manager that doesn’t show disk usage. Instead, use Resource Monitor and take a look! – Daniel B – 2017-05-10T14:00:36.713
@DanielB Note that i'm not complaining about the speed of the copy. Rather what Windows is doing to my system as it copies. I imagine if I wrote a perl script to copy the files 1 meg at a time with a one second pause after each, the system would be a lot faster. What am I looking for in Resource Monitor? It's just confirming that a large file is being copied, and that it's owned by an instance of Explorer. Setting that process to low priority doesn't seem to make a difference. – None – 2017-05-10T14:08:00.533
"What am I looking for in Resource Monitor?" - Disk Usage. Windows has to wait for I/O events to finish. Although if your system stops responding that indicates I/O errors are causing Windows to wait for the I/O event to finish. – Ramhound – 2017-05-10T14:10:23.137
“Priority” in Windows is CPU priority. I/O is not affected. Of course it’s not about the speed, it’s just that your storage device is near 100% busy copying stuff, which slows down other storage I/O. You can see this in Resource Monitor on the “Disk” tab in the “Storage” group. – Daniel B – 2017-05-10T14:12:06.173
@DanielB Yes, I'm looking at Resource Monitor now. Even non-storage related CPU usage is slowed though. I have a Putty session open to a Linux box, running Vim, and holding the j key down (to move the cursor down through the file) is really choppy. Even if Windows were to slow activity on each of the 8 cores on the PC if just one of them has triggered some disk activity, how does this explain Putty being slow? I still have 9 gigs of ram free so it's not swap related. – None – 2017-05-10T14:16:46.447
use ProcessHacker to set IO priority from normal to low for Explorer – magicandre1981 – 2017-05-10T15:21:59.313