Android OS Storage Usage I have two fresh Galaxy device on Android 9 , the difference is in storage , one is 512GB and another is 128GB. System usage in both is different , 128GB version uses 27GB on fresh but the 512GB version use up to 47GB. There is no installed app and both devices are just out of box.

My question is why Android uses more storage on 512GB version and how can I decrease the amount? If it's dynamic what's the reason and should it decrease if the device is out of storage?



I don't want to root both devices, so I checked it on another device which is previously rooted. By df -h I see it's about device partition, the rooted device is 32GB out of which only 25GB is available. Other partitions are listed as below:



As you can see there is some duplicate mounted partitions , but sum of their sizes will be 32GB.
With root take a comparison of space usage on both devices by executing du -h /data | sort -h. Without root you can rely on figures reported by filesystem by running df -h.

From the updated screenshot you have attached, no partition is duplicate mounted. If you are talking about tmpfs, it's a volatile filesystem which lives in RAM and is vanished on reboot. It isn't part of your persistent storage.

Your /data and /system added make 29GiB. That's what you get on a 32GB device. Up to 2GiB difference comes because of Gigabyte (GB) and Gibibyte (GiB). Also there are usually 50+ partitions on an Android device which aren't mounted (except a few filesystems). And there's free space left by manufacturers for over-provisioning of flash memory.

For details see: How disk space is used on Android device?