Is that based on observations or just an assumption? Microsoft use an even smaller threshold of 256KB in Windows Explorer, for example.[/quote]
It is based on observations and I could approve that on my own system (see below). As you can see in the test results, copying thousands of small files unbuffered is very smooth but takes 15 times longer than copying these files buffered (eating up the caches, leading to freezes).
MANY SMALL FILES TEST (BUFFERED + UNBUFFERED)
Source:
D:\Prj\ (contains 12.840 files, total-size of 987 MB)
2x Intel SSD (intern / RAID-0)
Target:
T:\Test
1x WD HDD (intern)
PS D:> Measure-Command {xcopy.exe D:\Prj*.* T:\Test\ /e}
BUFFERED: System lags a little and Perfmon shows caches growing. DOpus lags heavily, browsing the destination in parallel is only possible with short freezes (2-3 seconds).
Days : 0
Hours : 0
Minutes : 0
Seconds : 16
Milliseconds : 485
Ticks : 164852579
TotalDays : 0,000190801596064815
TotalHours : 0,00457923830555556
TotalMinutes : 0,274754298333333
TotalSeconds : 16,4852579
TotalMilliseconds : 16485,2579
PS D:> Measure-Command {xcopy.exe D:\Prj*.* T:\Test\ /e /j}
UNBUFFERED: System runs smooth and Perform shows constant caches. DOpus lags a little bit but browsing the destination in parallel is possible (near instant).
Days : 0
Hours : 0
Minutes : 3
Seconds : 28
Milliseconds : 757
Ticks : 2087572198
TotalDays : 0,00241617152546296
TotalHours : 0,0579881166111111
TotalMinutes : 3,47928699666667
TotalSeconds : 208,7572198
TotalMilliseconds : 208757,2198