Windows writes files to memory first before moving them to the HDD?

artins90 · 02 Feb 2018

I have been noticing this "weird" behavior lately, I noticed it when I attempted to decompress a very large archive containing many small files 2 days ago.
Basically the decompression speed was insane even for my my 7820x, between 150 and 200 MB/s.

After the decompression I noticed that my HDD was making quite a lot of noise for minutes after the decompression even though I wasn't running anything.
I then open the Task Manager and the Disk activity was indeed at 100%, but what's more interesting is that there were more than 2 GB of modified memory waiting to be written to the disk and this amount was slowly decreasing as the HDD kept writing. The 7zip process was nowhere to be found in the task manager.
I was able to replicate this by unzipping the same archive again.

This might be a neat performance improvement feature that allows the HDD to delay writes so that it can process them later when there might be less activity, but what if I lose power while are still in memory waiting to be written?

Currently I don't know if this is a feature or a weird issue, do you happen to have more info on this?

FreeBooter · 02 Feb 2018

The HDD is use to store data permanently, when a data stored or to be stored are always work on in system memory. Your computer uses RAM to load data because it's much quicker than running that same data directly off of a hard drive.

Josey Wales · 02 Feb 2018

I believe it goes into ROM and then to the Hard Drive-Read Only Memory.

Bree · 02 Feb 2018

artins90 said:

This might be a neat performance improvement feature that allows the HDD to delay writes so that it can process them later ... Currently I don't know if this is a feature or a weird issue, do you happen to have more info on this?

This is a design feature, more on how it works here....

By default, Windows caches file data that is read from disks and written to disks. This implies that read operations read file data from an area in system memory known as the system file cache, rather than from the physical disk. Correspondingly, write operations write file data to the system file cache rather than to the disk, and this type of cache is referred to as a write-back cache....

https://msdn.microsoft.com/en-us/lib...(v=vs.85).aspx

PiKo · 02 Feb 2018

Therefore I always use for external media "safely remove hardware and reject media", to prevent HDD or memory stick failure. Sometimes you will notice that it takes a while before blinking on the device stops and Windows says: removal is ok.