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Search "linux enable swap in a file" To enable a swap file in Linux, first create the swap file using a command like sudo dd if=/dev/zero of=/swapfile bs=1
by justsomehnguy 1y ago
Search "linux enable swap in a file"
To enable a swap file in Linux, first create the swap file using a command like sudo dd if=/dev/zero of=/swapfile bs=1G count=1 for a 1GB file. Then, set it up with sudo mkswap /swapfile and activate it using sudo swapon /swapfile. To make it permanent, add /swapfile swap swap defaults 0 0 to your /etc/fstab file.
- awesome_dude 1y agoStrongly suggest you try doing that on a VPS, then report back
- ahepp 1y agoWhat do you think is going to happen? I tested it out on an ec2 instance just now and it seems to have worked as one would expect.
- awesome_dude 1y agoEC2 != VPS
- Zekio 1y agowell once you "need" that swap, it will be writing pages across the network due to the storage being external to the physical server, so the latency is terrible
- kassner 1y agoPut swap on the “instance store” disk, not EBS.
- ahepp 1y agoLatency of swap is always terrible in comparison to RAM. RAM vs disk is already something ~1000x right? I've never characterized EBS vs trad ssd, but I would be surprised if it's more than 10x. I don't think using swap as "emergency RAM" makes a lot of sense in 2025. The arguments in favor of swap which I find convincing are about allowing the system to evict low use pages which otherwise would not be evictable.
- justsomehnguy 1y agohttps://news.ycombinator.com/item?id=45007821 https://news.ycombinator.com/item?id=45007821 And that was like... two years ago? 1GB of RAM and actually ~700MB usable before I found the proper magik incantations to really disable kdump. Also have used 1GB machines for literally years. Strongly suggest you shouldn't strongly suggest.
- awesome_dude 1y agoUh.. your link... doesn't show how a VPS can have SWAP enabled You do understand what's being discussed... right?
- justsomehnguy 1y agoLiterally up the chain: https://news.ycombinator.com/item?id=45663111 https://news.ycombinator.com/item?id=45663111 Or you have a very peculiar understanding what 'VPS' means.
- awesome_dude 1y agohttps://en.wikipedia.org/wiki/Virtual_private_server https://en.wikipedia.org/wiki/Virtual_private_server As I said earlier https://news.ycombinator.com/threads?id=awesome_dude#45663117 https://news.ycombinator.com/threads?id=awesome_dude#4566311...
- justsomehnguy 1y agoHello, it's the year 2025 here. If you use OpenVZ-like ancient shit - it's on you. So no, VPS is a proper virtualization for a 15 years. And with a proper virtualization you have the full control.
- collinmanderson 1y agoYes. I think might also need to chmod 600 /swapfile. I do this on all my VPS, especially helps for small VPS with only 1GB ram: fallocate -l 1G /swapfile chmod 600 /swapfile mkswap /swapfile swapon /swapfile Works really well with no problems that I've seen. Really helps give a bit more of a buffer before applications get killed. Like others have said, with SSD the performance hit isn't too bad.
- awesome_dude 1y agoIME SWAP has been explicitly disabled by the VPS providers. Partly it's a money thing (they want to sell you RAM), partly it's so that the shared disk isn't getting thrashed by multiple VPS
- efreak 1y agoGet better VPS then. Openvz and other kernel paravirtualization have limits, go for Xen or KVM instead (Xen has paravirtualization as well, but I'm not sure how much it's actually used). Full virtualization (implemented by Xen and KVM) do not allow you to prevent swap from being used.
- collinmanderson 1y agoI forgot to mention what the parent comment said, yes, need to put something like this in /etc/fstab: /swapfile swap swap sw 0 0 or via ansible: mount: src: "/swapfile" name: "swap" fstype: "swap" opts: "sw" passno: "0" dump: "0" state: present