一、redhat
swap partition - recommended size at least 1 GB
Swap file systems support virtual memory; data is written to a swap file system when there is not enough RAM to store the data your system is processing. Swap size is a function of system memory workload, not total system memory and therefore is not equal to the total system memory size. Therefore, it is important to analyze what applications a system will be running and the load those applications will serve in order to determine the system memory workload. Application providers and developers should be able to provide some guidance.
When the system runs out of swap space, the kernel terminates processes as the system RAM memory is exhausted. Configuring too much swap space results in storage devices being allocated but idle and is a poor use of resources. Too much swap space can also hide memory leaks. The maximum size for a swap partition and other additional information can be found in the mkswap(8) manual page.
The following table provides the recommended size of a swap partition depending on the amount of RAM in your system and whether you want sufficient memory for your system to hibernate. If you let the installation program partition your system automatically, the swap partition size will be established using these guidelines. Automatic partitioning setup assumes hibernation is not in use. The maximum size of the swap partition is limited to 10% of the total size of the hard drive, and the installer cannot create swap partitions more than 128GB in size. If you want to set up enough swap space to allow for hibernation, or if you want to set the swap partition size to more than 10% of the system's storage space, or more than 128GB, you must edit the partitioning layout manually.
Table 8.3. Recommended System Swap Space
|
Amount of RAM in the system |
Recommended swap space |
Recommended swap space if allowing for hibernation |
|
less than 2 GB |
2 times the amount of RAM |
3 times the amount of RAM |
|
2 GB - 8 GB |
Equal to the amount of RAM |
2 times the amount of RAM |
|
8 GB - 64 GB |
4GB to 0.5 times the amount of RAM |
1.5 times the amount of RAM |
|
more than 64 GB |
workload dependent (at least 4GB) |
hibernation not recommended |
At the border between each range listed above (for example, a system with 2 GB, 8 GB, or 64 GB of system RAM), discretion can be exercised with regard to chosen swap space and hibernation support. If your system resources allow for it, increasing the swap space can lead to better performance.
Distributing swap space over multiple storage devices - particularly on systems with fast drives, controllers and interfaces - also improves swap space performance.
二、centos
官網地址：https://docs.centos.org/en-US/centos/install-guide/CustomSpoke-x86/#sect-partitioning-advice
centos和redhat的官網文檔對swap partition的建議是一樣的。
swap partition - recommended size at least 1 GB
Swap file systems support virtual memory; data is written to a swap file system when there is not enough RAM to store the data your system is processing. Swap size is a function of system memory workload, not total system memory and therefore is not equal to the total system memory size. Therefore, it is important to analyze what applications a system will be running and the load those applications will serve in order to determine the system memory workload. Application providers and developers should be able to provide some guidance.
When the system runs out of swap space, the kernel terminates processes as the system RAM memory is exhausted. Configuring too much swap space results in storage devices being allocated but idle and is a poor use of resources. Too much swap space can also hide memory leaks. The maximum size for a swap partition and other additional information can be found in the mkswap(8) manual page.
The following table provides the recommended size of a swap partition depending on the amount of RAM in your system and whether you want sufficient memory for your system to hibernate. If you let the installation program partition your system automatically, the swap partition size will be established using these guidelines. Automatic partitioning setup assumes hibernation is not in use. The maximum size of the swap partition is limited to 10% of the total size of the hard drive, and the installer cannot create swap partitions more than 128GB in size. If you want to set up enough swap space to allow for hibernation, or if you want to set the swap partition size to more than 10% of the system’s storage space, or more than 128GB, you must edit the partitioning layout manually.
|
Amount of RAM in the system |
Recommended swap space |
Recommended swap space if allowing for hibernation |
|
less than 2 GB |
2 times the amount of RAM |
3 times the amount of RAM |
|
2 GB - 8 GB |
Equal to the amount of RAM |
2 times the amount of RAM |
|
8 GB - 64 GB |
4GB to 0.5 times the amount of RAM |
1.5 times the amount of RAM |
|
more than 64 GB |
workload dependent (at least 4GB) |
hibernation not recommended |
At the border between each range listed above (for example, a system with 2 GB, 8 GB, or 64 GB of system RAM), discretion can be exercised with regard to chosen swap space and hibernation support. If your system resources allow for it, increasing the swap space can lead to better performance.
Distributing swap space over multiple storage devices - particularly on systems with fast drives, controllers and interfaces - also improves swap space performance.
三、Ubuntu
How much swap do I need?
For less then 1GB of physical memory (RAM), it's highly recommended that the swap space should, as a base minimum, be equal to the amount of RAM. Also, it's recommended that the swap space is maximum twice the amount of RAM depending upon the amount of hard disk space available for the system because of diminishing returns.
For more modern systems (>1GB), your swap space should be at a minimum be equal to your physical memory (RAM) size "if you use hibernation", otherwise you need a minimum of round(sqrt(RAM)) and a maximum of twice the amount of RAM. The only downside to having more swap space than you will actually use, is the disk space you will be reserving for it.
The "diminishing returns" means that if you need more swap space than twice your RAM size, you'd better add more RAM as Hard Disk Drive (HDD) access is about 10³ slower then RAM access, so something that would take 1 second, suddenly takes more then 15 minutes! And still more then a minute on a fast Solid State Drive (SSD)...
Example Scenarios
(last 3 columns denote swap space)
RAM No hibernation With Hibernation Maximum
256MB 256MB 512MB 512MB
512MB 512MB 1024MB 1024MB
1024MB 1024MB 2048MB 2048MB
RAM No hibernation With Hibernation Maximum
1GB 1GB 2GB 2GB
2GB 1GB 3GB 4GB
3GB 2GB 5GB 6GB
4GB 2GB 6GB 8GB
5GB 2GB 7GB 10GB
6GB 2GB 8GB 12GB
8GB 3GB 11GB 16GB
12GB 3GB 15GB 24GB
16GB 4GB 20GB 32GB
24GB 5GB 29GB 48GB
32GB 6GB 38GB 64GB
64GB 8GB 72GB 128GB
128GB 11GB 139GB 256GB
256GB 16GB 272GB 512GB
512GB 23GB 535GB 1TB
1TB 32GB 1056GB 2TB
2TB 46GB 2094GB 4TB
4TB 64GB 4160GB 8TB
8TB 91GB 8283GB 16TB
四、fedora
官網地址（fedora 26）：https://docs.fedoraproject.org/en-US/Fedora/26/html/Installation_Guide/sect-installation-gui-manual-partitioning-recommended.html
fedora和redhat8也是一樣的
swap - based on your system parameters
Swap partitions support virtual memory; data is written to them when there is not enough RAM to store the data your system is processing. This partition's size is a function of system memory workload, not total system memory, and therefore is not equal to the total system memory size. Therefore, it is important to analyze what applications a system will be running and the load those applications will serve in order to determine the system memory workload. Application providers and developers should be able to provide some guidance.
When the system runs out of swap space, the kernel terminates processes as the system RAM memory is exhausted. Configuring too much swap space results in storage devices being allocated but idle and is a poor use of resources. Too much swap space can also hide memory leaks. The maximum size for a swap partition and other additional information can be found in the mkswap(8) man page.
The table below provides the recommended size of a swap partition depending on the amount of RAM in your system and whether you want sufficient memory for your system to hibernate. If you let the installation program partition your system automatically, the swap partition size will be established using these guidelines. Automatic partitioning setup assumes hibernation is not in use, and the maximum size of the swap partition is limited to 10% of the total size of the hard drive. If you want to set up enough swap space to allow for hibernation, or if you want to set the swap partition size to more than 10% of the system's storage space, you must edit the partitioning layout manually.
Table 5.2. Recommended System Swap Space
| Amount of RAM in the system | Recommended swap space | Recommended swap space if allowing for hibernation |
|---|---|---|
| less than 2 GB | 2 times the amount of RAM | 3 times the amount of RAM |
| 2 GB - 8 GB | Equal to the amount of RAM | 2 times the amount of RAM |
| 8 GB - 64 GB | 0.5 times the amount of RAM | 1.5 times the amount of RAM |
| more than 64 GB | workload dependent | hibernation not recommended |
At the border between each range listed above (for example, a system with 2 GB, 8 GB, or 64 GB of system RAM), discretion can be exercised with regard to chosen swap space and hibernation support. If your system resources allow for it, increasing the swap space may lead to better performance.
Distributing swap space over multiple storage devices - particularly on systems with fast drives, controllers and interfaces - also improves swap space performance.