Hey there,
Just curious if anyone has any insight as to why after performing a Synchronize Update to a fresh drive produces over 2TB more space utilization on a target drive vs. the original.
Environment:
MacOS Big Sur 11.1
MacMini M1 - 8G ram
Original Disk G-Technology 12TB Raid0
Target Disk - 2 WD 12TB drives mirrored with Apple Raid Utility
Starting with a fresh empty Mirror and simply performing the Synchronize Update these are the results:
Get Info comparison after migration using FreeFileSync.jpg (223.4 KiB) Viewed 778 times
I know nothing of Mac, but might Thunderbolt be doing some sort of automatic compression (& taking that into account for the Used: number), that might be off or not available on the Mirror end?
I wouldn't think that the transport has any affect on how the operating system writes to the drives other than speed. I was thinking that possibly the G-Technology enclosure was doing some compression on the way in but there tech folks won't admit to that.
Even the Finder copy produces the same result and I've tried all chunk sizes. Went back to the 32k default for the smallest amount of overhead.
Not that I'm understanding what's being said, but maybe something like applies?:
Are you using file-based virtual memory on this SSD?
Opening a handle to a raw volume will cause file-based virtual memory to be allocated on disk.
Everything will open a handle to your raw volumes to monitor changes to your file system.
To check disk activity:
In the Resource Monitor (Start -> Resource Monitor)
Click the Disk tab
Expand Disk Activity
What image is writing to your disk?
Actually copying to a WD drive (not SSD). Volume is not raw but formatted for HFS+ since it is a spinning disk. The copy is not an image but rather individual files.
Interesting that the file sizes of individual folders match up exactly but when everything is complete the free space calculation is 2TB different.
