zRAM
Also known as: zram android, compressed swap, zram android
zRAM is a Linux kernel feature, used widely on Android, that creates a compressed block device in RAM and uses it as swap. Idle memory pages are compressed in place rather than written to flash, easing memory pressure without touching your file storage.
- zRAM is a compressed in-RAM swap device, not swap written to flash.
- It uses fast compressors like lz4 or zstd, trading CPU for memory headroom.
- Enabled by default on most Android phones; OEMs may brand it as RAM Plus.
How zRAM works
zRAM creates a virtual swap device that lives inside RAM. When the kernel needs to reclaim memory, it compresses idle anonymous pages (using algorithms such as lz4 or zstd) and stores the compressed data in the zRAM region instead of writing them to the flash that holds your files. Reactivating a page decompresses it back into normal RAM.
The effect is that a device behaves as if it has somewhat more RAM than is physically installed, because compressible pages take up less space while swapped. Compression and decompression cost CPU cycles, so zRAM trades a little processing for reduced memory pressure and far fewer (or zero) writes to flash storage compared with traditional disk swap.
zRAM on Android
Most modern Android devices enable zRAM by default; OEMs sometimes brand the resulting headroom as "RAM Plus," "Virtual RAM," or "RAM expansion," though some of those features also reserve a slice of internal storage. zRAM is part of why Android can keep more apps warm in the background and is preferred over file-backed swap to protect flash endurance and battery.
Because zRAM operates on memory, it does not increase usable file storage and is not something an app cleaner manages. Clearing app cache, junk files, and duplicate photos frees disk capacity; zRAM independently reduces how often the system has to kill background apps. The two solve different problems: storage versus memory.