Forum Discussion
alexfreu
Oct 31, 2019Copper Contributor
BrowserMetrics
There is a folder %localappdata%\Microsoft\Edge Dev\User Data\BrowserMetrics with thousands of 4 MB files like BrowserMetrics-5D3A8F5A-1AF0.pma that fill up my precious SSD disk space. Can I remove ...
lexcyn
Mar 30, 2021Iron Contributor
Thanks - done as requested.
I just cleared out the files a couple of days ago and already up to over 12k new files, all spaced 1 day apart. Added all the details into a txt file in the upload!
I just cleared out the files a couple of days ago and already up to over 12k new files, all spaced 1 day apart. Added all the details into a txt file in the upload!
JimGrisham
Mar 31, 2021Iron Contributor
lexcynHow far apart are the dates/times on your files? [Unless my quick math is wrong, 12,000 files over 2 days (48 hours) would be 250/hour, or a new file every 15 seconds or less. Even if over 4 days (96 hours), that is 125 files/hour, still over 2 new files _per minute_.]
dave260 Here's probably why the NTFS file compression isn't working for you:
- When NTFS compression is enabled on a file:
- The file is broken up into small sections
- Every time one of those sections is written to,
- The data for that section (including any changes being saved) are compressed in RAM.
- If the compressed size is smaller than the size of the uncompressed data, the compressed section is written to disk.
- If the compressed size is about the same or larger than the uncompressed data, that section is written uncompressed
- The data for that section (including any changes being saved) are compressed in RAM.
- What I think Edge is doing:
- Creates a new empty 4MB file
- 'Memory-maps' that file to an area of memory so that Edge can write to it directly
- Each time it has a drop of 'metrics' data, it stores it in RAM
- Since the file is 'memory-mapped', the system (Windows' virtual memory subsystem and/or the CPU's internal Memory Management Unit) automatically writes the changed data to disk, some small number of bytes at a time
- Since only a tiny bit of data is changing at any one moment, NTFS compression doesn't bother with it (guesses: because it's either too small, because by itself it doesn't compress well, or because it never really works for memory-mapped files)
If you were to turn off compression for your entire BrowserMetrics folder and its contents, and them immediately turned it back on, I think you'd find that all existing files would be greatly compressed, but new files would not. So much for that idea!