zram compressed RAM block device
A virtual block device that stores its contents in RAM in compressed form. It is most commonly used as a swap device — letting the system effectively fit more pages into memory by compressing cold ones — and is also used for compressed /tmp and caches. It is the default swap mechanism on Fedora, recent Debian, Arch, and most Android phones.
recommendation
It should stay in the kernel because zram is one of the most widely deployed pieces of Linux memory-management plumbing in 2025: Fedora, Debian 12+, Arch, and many Android devices use it as their default swap backend via systemd's zram-generator. Upstream development is clearly active, with 2025 patches adding asynchronous writeback and 2026 RFC work on per-backend compression streams, and there is no equivalent replacement (zswap is related but solves a different problem).
repository signals
sources
- docs.kernel.org
Official kernel documentation describes zram as a compressed RAM-backed block device used for swap, /tmp, and caches; it is a virtual software block driver rather than hardware support.
- lkml.org
A 2025 patch series proposed asynchronous writeback support for zram, showing active upstream feature development rather than removal.
- lwn.net
An RFC patch series from March 2026 discusses letting zram compression backends manage their own streams, further indicating ongoing upstream work.
- fedoraproject.org
Fedora documents swap-on-zram as a default system feature, demonstrating mainstream current deployment.
- github.com
The systemd zram-generator project documents packaged support for Fedora, Debian 12+, and Arch, indicating ongoing new deployments across current distributions.
codex reasoning notes (technical)
Local inspection via shell (`rg`, `sed`) confirmed `drivers/block/zram` is the kernel's compressed RAM block-device driver with current docs and feature Kconfig options. Lore access via `lei` was unavailable in shell, so lore/mailing-list evidence was gathered with web search: LKML/Spinics/LWN results showed 2025-2026 feature work and cleanups, and I found no removal/deprecation series in those searches. Deployment evidence came from web search results for Fedora's SwapOnZRAM change page and the systemd `zram-generator` project, which show current distro use. Because zram is a virtual software driver, `hardware_still_sold_new_in_2025` is false and `last_widely_available_year` is null. There is no clear one-for-one upstream replacement driver; `zswap` is adjacent but not equivalent.