Swap but better it behave mostly like actual ram and fast too, not as fast as actual ram but still way faster than swap I can open 5 browser tabs one of them playing a video while compiling a software I don’t feel my system slow down at all
From my understanding, it’s the opposite. Zswap is the better one since it has a ZRAM-like compressed section of RAM and disk-backed swap. That’s definitely an oversimplification though.
I agree it’s confusing. I always look it up during setup so I know which one to use.
There is a lengthy thread on Reddit about the technical differences. Apparently Zswap will take advantage of the kernel eviction strategy for swap space. Apparently Zram doesn’t have that. To me that never made sense because, you create a Zram block device and then set that as your storage for swap space. Why would the kernel care, or know, that the swap space is backed by a Zram block device.
I do use Zram for my cloud self hosting machines and my dev machine. On the cloud devices they have 1 or 2 GB of ram and on my dev machine I have 32GB of ram. And in both cases it definitely seems like there is swap eviction. I also set the vm.swappiness to 180. Prior to Zram I would set my machines’ swappiness to 10. Swapping is highly encouraged on my machine.
But… Why? If ZRam uses RAM as compressed swap, what advantage does it have over just leaving that RAM available as shared memory? Do you have a specific process that is eating up non-shared? This might be of interest: https://chrisdown.name/2026/03/24/zswap-vs-zram-when-to-use-what.html
You get more ram for very little slow down, that also, would rarely be the bottleneck. For the servers, ram is a constraint, and it’s all just selfhosting. I have a Raspberry Pi that I selfhost with, as well as a couple 10 dollar compute instances in the cloud. More ram is much better than the tiny slow down that might occur during compression or decompression. All my services are all still very snappy, even the mailserver. For my work, I bring up large docker sandboxes of services that I need running to test entire systems. In the past, I would just allocate 32GB to a swapfile. ZRam is way faster.
But you also get that with shared memory in zswap, with all the other advantages. I’d really recommend reading the “Architectural differences” in the linked article from Chris Down, as he’s way deeper into the kernel code than me, but the biggest problem in a setup like a small memory server is:
If you have a ZRAM device, and it fills up, more recently needed pages end up on the backup disk swap, because ZRAM has no way to move between swaps
Where zswap is built into the kernel memory management layer, so it can automatically decide which pages are cold and put them on disk, while keeping fresh ones in compressed RAM.
I.E. in your use case, zswap is better, not even taking into account all the other details from Chris’ article.
It’s the opposite actually, in terms of implementation Zram is a hack, but it does have it’s use case when your system load doesn’t far exceed your total RAM, on the other hand swap is tightly integrated into the system and it’s on it’s way to implement “Virtual Swap” which is effectively Zram but not a hack, making it like a hundred times better, see This blogpost for a detailed explanation
Swap but better it behave mostly like actual ram and fast too, not as fast as actual ram but still way faster than swap I can open 5 browser tabs one of them playing a video while compiling a software I don’t feel my system slow down at all
I always confuse ZRAM and ZSwap. From my understanding ZRAM is the better one and Zswap is kinda outmoded.
It turns into a rabbit hole every time I gotta reference it! Lol
From my understanding, it’s the opposite. Zswap is the better one since it has a ZRAM-like compressed section of RAM and disk-backed swap. That’s definitely an oversimplification though.
I agree it’s confusing. I always look it up during setup so I know which one to use.
There is a lengthy thread on Reddit about the technical differences. Apparently Zswap will take advantage of the kernel eviction strategy for swap space. Apparently Zram doesn’t have that. To me that never made sense because, you create a Zram block device and then set that as your storage for swap space. Why would the kernel care, or know, that the swap space is backed by a Zram block device.
I do use Zram for my cloud self hosting machines and my dev machine. On the cloud devices they have 1 or 2 GB of ram and on my dev machine I have 32GB of ram. And in both cases it definitely seems like there is swap eviction. I also set the vm.swappiness to 180. Prior to Zram I would set my machines’ swappiness to 10. Swapping is highly encouraged on my machine.
Why not just set kernel swappiness to 1 and not do any of that?
Because I want to encourage more swapping, not less.
But… Why? If ZRam uses RAM as compressed swap, what advantage does it have over just leaving that RAM available as shared memory? Do you have a specific process that is eating up non-shared? This might be of interest: https://chrisdown.name/2026/03/24/zswap-vs-zram-when-to-use-what.html
You get more ram for very little slow down, that also, would rarely be the bottleneck. For the servers, ram is a constraint, and it’s all just selfhosting. I have a Raspberry Pi that I selfhost with, as well as a couple 10 dollar compute instances in the cloud. More ram is much better than the tiny slow down that might occur during compression or decompression. All my services are all still very snappy, even the mailserver. For my work, I bring up large docker sandboxes of services that I need running to test entire systems. In the past, I would just allocate 32GB to a swapfile. ZRam is way faster.
But you also get that with shared memory in zswap, with all the other advantages. I’d really recommend reading the “Architectural differences” in the linked article from Chris Down, as he’s way deeper into the kernel code than me, but the biggest problem in a setup like a small memory server is:
If you have a ZRAM device, and it fills up, more recently needed pages end up on the backup disk swap, because ZRAM has no way to move between swaps
Where zswap is built into the kernel memory management layer, so it can automatically decide which pages are cold and put them on disk, while keeping fresh ones in compressed RAM.
I.E. in your use case, zswap is better, not even taking into account all the other details from Chris’ article.
It’s the opposite actually, in terms of implementation Zram is a hack, but it does have it’s use case when your system load doesn’t far exceed your total RAM, on the other hand swap is tightly integrated into the system and it’s on it’s way to implement “Virtual Swap” which is effectively Zram but not a hack, making it like a hundred times better, see This blogpost for a detailed explanation