But did you turn off Windows automatically scheduled defrag to cut down wear on the SSD?
I have a Samsung 840 EVO SSD (250GB) and have noticed slowly disappearing free space on the drive. The drive is set as a boot drive on a Windows 7 system (user folders are on a regular HDD). The drive has multiple partitions, but I am only talking about a 200GB partition for booting Windows (Windows folder, Program Files folder, ProgramData folder, etc), not any recovery partitions, boot blocks, or overprovisioning space (which is on a different partition completely). I began noticing that space appeared to be decreasing at a fairly regular rate (about 1GB every day or so). In my initial research, I found this is apparently a common problem and likely does not only affect Samsung drives, but drives by all manufacturers, and appears to happen not only with Windows systems, but OS X and Linux as well.
It initially seemed that the vanishing space was due to Windows temp files, system restore files, and the like. System restore on this partition had been disabled when I installed it. I then did a file size count and it appeared that there was around 30GB of space unaccounted for. I tried running chkdsk and it matched what Windows had reported for used & free space and found no issues. Time for some bigger guns.
I tried GPartEd and again got the same used & free space numbers Windows reported. My worry was there was some growing "super hidden" file(s), maybe even some insidious malware taking up space (not long ago on a different system, I had this very problem where there was a hypervisor OS installed above Windows on a hidden partition with full remote control). I still could not believe there was 30GB worth of files from normal Windows operations that are unaccounted for.
Since GPartEd runs under Linux, I can bypass all of the Windows security restrictions and see all the files, which included about 100MB worth of files in the "empty" system restore folder. I selected every single file and folder on the root of the partition and did a "Properties" to get a count. Again, the byte count of all the files was about 30GB below the reported used space. Again, I'm doing this check under a Linux boot, so every single folder and file is accessible. I then ran Disk Usage Analyzer, and again the sum total of all the files was about 30GB short of the reported used space.
I then tried both WinDirStat and TreeSize (free) under Windows. They both found and "unknown" area the size of my "missing" space. The space show as one large block and was completely inaccessible with no attached file names. As if this was an allocated area of nothing. I even tried running both apps under a SYSTEM login, and STILL could not determine what this 30GB block of used space was.
My next thought was this might be some "garbage collection" issue with the SSD. Maybe the TRIM function is not working right. I ran the Performance Optimization in the Samsung Magician. There was no change. I tried forcing Windows to run its own TRIM routine. No change. I even tried running the drive without a data cable for several hours (but with the power cable connected) in hopes the internal firmware would do its thing with an idle drive. No change.
I then cleared all the temp files and browser caches. I recovered some space, but the amount of used space went down as the free space went up by the same amount, so that 30GB block is still unaccounted for. I then kept a close eye on the used space, I still see the space creeping down. I started my investigation into this at the beginning of the month. Since then, the missing space has grown from about 30GB to about 70GB.
As I mentioned, I did a lot of digging around and most of the answers explained the missing files as due to the Windows system restore folders, page files, hibernation files, and other files, which seemed to satisfy the poster, but did not answer it correctly. I also saw this issue posted in Apple and Linux boards, but they had no explanations of what was the cause of the missing space nor a way to recover it. And again, this appears to be a fundamental issue with SSDs as the threads I've read mention a number of different brand drives.
Anyone else experience this? Anyone have a solution?

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