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Is it normal that Windows’s automatic SSD optimisation / re-trim sometimes generates a lot of writes?

Hi,

About one month ago, I got a new PC with only SSDs and I have been watching closely how much data has been written. Twice so far, I have noticed in SeaTools that when Windows performs its automatic drive optimization (I left it on the default “Weekly” setting), a lot of writes were added to the SSD : a few days after installing Windows, about 36 GB, and today, over 20 GB suddenly. I am sure that it’s not because of another program or Windows updates. I have been getting few writes in general in the past days and didn’t install any new program either. That’s the SSD Windows is installed on ; I have another one that only got much smaller TBW increases because of Windows’s optimization.

My question is : is this normal, especially considering that my SSD only has 71.5 GiB of space used (2 TB total)? I know that Windows may sometimes have to defragment an SSD (https://www.hanselman.com/blog/the-real-and-complete-story-does-windows-defragment-your-ssd), but this is supposed to be once a month only.

I couldn’t find anything else about this question on the web, besides people saying that re-trim shouldn’t do anything if TRIM could happen normally in the first place and that it shouldn’t cause additional wear on the drive, but maybe that’s wrong ?

Could a reason this is happening be that after Windows re-trims it, the drive decides to move data around because of wear-levelling ?

Thank you

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  • Yes, Windows does this. I stumbled onto that too when my incremental backups were 'randomly' big. It's just one of many many thing that are terribly broken about Windows and especially NTFS. The issue is that the scheduled task performs media-specific "optimizations" by default, which in case of SSD does normally only mean retrim, but every so often also an actual defrag. I disabled the task and do it manually now. You still have "live" trims when you deleted files, at least on NVMe, I think it's off for SATA drives though, as many are buggy with it.

    Another really stupid thing is that you should disable shadow copies, otherwise it can happen that data gets written as many times as you have (persistent) shadow copies, eg writing 1G with 6 shadow copies -> 6G written. Absolutely insane.

    You often hear this type of "internet wisdom" repeated from decades ago that all this is a solved problem, but it's really not and no one cares about fixing these fundamental issues at Microsoft. They did seemingly pick up work on ReFS again, but from reports it's still very buggy and who knows if it will be ready for Windows 12 next year or if that is even their goal.