Is swap necessary for Linux?
Can you use Linux without swap? Yes, you can, especially if your system has plenty of RAM. But as explained in the previous section, a little bit of swap is always advisable. In fact, a distribution like Ubuntu automatically creates a swap file of 2 GB in size.
Without swap, the OS has no choice but to keep the modified private memory mappings associated with those services in RAM forever. That's RAM that can never be used as disk cache. So you want swap whether you need it or not.
Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM.
The short answer is, No. There are performance benefits when swap space is enabled, even when you have more than enough ram. Update, also see Part 2: Linux Performance: Almost Always Add Swap (ZRAM). …so in this case, as in many, swap usage is not hurting Linux server performance.
| Amount of RAM installed in system | Recommended swap space | Recommended swap space with hibernation |
|---|---|---|
| ≤ 2GB | 2X RAM | 3X RAM |
| 2GB – 8GB | = RAM | 2X RAM |
| 8GB – 64GB | 4G to 0.5X RAM | 1.5X RAM |
| >64GB | Minimum 4GB | Hibernation not recommended |
...
How much should be the swap size?
| RAM Size | Swap Size (Without Hibernation) | Swap size (With Hibernation) |
|---|---|---|
| 8GB | 3GB | 11GB |
| 12GB | 3GB | 15GB |
| 16GB | 4GB | 20GB |
| 24GB | 5GB | 29GB |
"will (typically) not have a use" is quite different than "will automatically disable". Actually, Ubuntu is never disabling swap and will make use of it if it needs to, even if you have 8GB of RAM or more.
Once the physical memory is used up, swap gets used. As the swap disk is much slower than RAM, the performance goes down, and thrashing occurs. At this point, even logins into the system might become impossible.
With no swap, the system will run out of virtual memory (strictly speaking, RAM+swap) as soon as it has no more clean pages to evict. Then it will have to kill processes.
The primary function of swap space is to substitute disk space for RAM memory when real RAM fills up and more space is needed. For example, assume you have a computer system with 8GB of RAM. If you start up programs that don't fill that RAM, everything is fine and no swapping is required.
Is it OK to disable swap?
No it is not safe. The reason is that when the system runs out of RAM and will be unable to swap any of it, it might freeze with no chance for recovery other than a hard reset.
Run swapoff -a: this will immediately disable the swap. Remove any swap entry from /etc/fstab. Get the system rebooted. Ok, if the swap is gone.
Swap in Linux is a space on a disk drive (HDD or SSD) that is used when the amount of physical memory (RAM) tends to get full. Although it protects Linux system from getting out of memory, in certain cases it is recommended to disable swap.
Swap will automatically be reinstated after rebooting if swap is announced in /etc/fstab .
The swap partition serves as overflow space for your RAM. If your RAM fills up completely, any additional applications will run off the swap partition rather than RAM. This may sound like an easy way to increase your computer's amount of usable memory without actually getting more RAM, but that isn't the case.
/ (Linux system)
Now select the rest of the free space to create the root partition. Ubuntu recommends at least 15GB for the system partition. However, if you want to play games and install many programs, I recommend 50GB or even 100GB. It depends on the size of your hard drive and your needs.
The swap partition is an independent section of the hard disk used solely for swapping; no other files can reside there. The swap file is a special file in the filesystem that resides amongst your system and data files. Each line lists a separate swap space being used by the system.
Swap is disk space reserved for if you run out of RAM. Hibernate is the ability to save all RAM to disk and power off. In resume, the swap can be loaded to RAM for theoretically faster resume and to get back exactly where you left off. I run with no swap.
- Turn off the existing swap space.
- Create a new swap partition of the desired size.
- Reread the partition table.
- Configure the partition as swap space.
- Add the new partition/etc/fstab.
- Turn on swap.