From 4eacf14fbc7f627b0a9d6c138163a83b0f485553 Mon Sep 17 00:00:00 2001 From: darksun Date: Thu, 21 Dec 2017 16:54:42 +0800 Subject: [PATCH] =?UTF-8?q?=E9=80=89=E9=A2=98:=20Creating=20SWAP=20partiti?= =?UTF-8?q?on=20using=20FDISK=20&=20FALLOCATE=20commands?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...tition using FDISK & FALLOCATE commands.md | 118 ++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 sources/tech/20170802 Creating SWAP partition using FDISK & FALLOCATE commands.md diff --git a/sources/tech/20170802 Creating SWAP partition using FDISK & FALLOCATE commands.md b/sources/tech/20170802 Creating SWAP partition using FDISK & FALLOCATE commands.md new file mode 100644 index 0000000000..0a8bfb8fa0 --- /dev/null +++ b/sources/tech/20170802 Creating SWAP partition using FDISK & FALLOCATE commands.md @@ -0,0 +1,118 @@ +translating by lujun9972 +Creating SWAP partition using FDISK & FALLOCATE commands +====== +Swap-partition holds the memory which is used in case the physical memory (RAM) is full . When RAM capacity has been utilized to maximum , Linux machine moves inactive pages from memory to swap-space which are then used by the system. Though it gets the work done, it should not be considered as a replacement to physical memory/RAM. + +In most cases, it is advised to keep SWAP-memory equal to size of physical memory at minimum & double the size of physical memory at maximum. So if you have 8 GB RAM on your system, Swap should be between 8-16 GB. + +If a swap-partition has not been configured in your Linux system, your system might start killing off the running process/applications & might cause your system to crash. In this tutorial, we will learn to add swap-partition to Linux system & we will be discussing two methods for creating a swap-partition + + * **Using fdisk command** + * **Using fallocate command** + + + +### First Method (Using Fdisk command) + +Normally, first hdd of the system is named **/dev/sda** & partitions for it are named **/dev/sda1** , **/dev/sda2**. For this tutorial we will using a HDD that have 2 primary partitions on system i.e. /dev/sda1, /dev/sda2 & SWAP will be /dev/sda3. + +Firstly we will create a partition, + +``` +$ fdisk /dev/sda +``` + +to create a new partition type **' n'** . You will now be asked to enter the first cylinder value, just hit enter key to use default value & then you will asked to enter last cylinder value, here we will enter the size of swap partition (we will be using 1000MB). Enter the value in last cylinder as +1000M. + +![swap][2] + +We have now created a partition of size 1000MB but we have not assigned it any partition type, so to assign a partition type, press **" t"** & press enter. + +Now you will be first asked to enter partition number, which is **3** for our partition & then we will asked to enter partition id which for swap it's **82** (to see list of all available partition types, press **" l"** ) & then press " **w "** to save the partition table. + +![swap][4] + +Next we will format our swap partition using mkswap command + +``` +$ mkswap /dev/sda3 +``` + +& will then activate our newly created swap + +``` +$ swapon /dev/sda3 +``` + +But our swap will not be mounted automatically after every reboot. To mount it permanently in our system, we need to append /etc/fstab file. Open /etc/fstab file & make an entry of the following line + +``` +$ vi /etc/fstab +``` + +``` +/dev/sda3 swap swap default 0 0 +``` + +Save & close the file. Our swap now will even work after a reboot. + +### Second Method (using fallocate command) + +I prefer this method as this is easiest & fastest way to create swap. Fallocate is one of the most underestimated & very less used command. Fallocate is used to pre-allocate blocks/size to a files. + +To create a swap using fallocate, we will firstly create a file named **swap_space** in ** '/'**. Next we will allocate 2GB to our file swap_space , + +``` +$ fallocate -l 2G /swap_space +``` + +We will then verify the size of the file by running + +``` +ls-lh /swap_space. +``` + +Next, we will make our /swap_space more secure by changing the file permissions + +``` +$ chmod 600 /swap_space** +``` + +Now only root will be able to read, write on this file. We will now format the swap partition, + +``` +$ mkswap /swap_space +``` + +& then will turn on our swap + +``` +$ swapon -s +``` + +This swap partition will need to be remounted after every reboot. So to make it permanent, edit the /etc/fstab, as we did above & enter the following line + +``` +/swap_space swap swap sw 0 0 +``` + +Save & exit the file. Our swap will now be permanently mounted. We can check if your swap is working or not by running " **free -m** " on your terminal after rebooting the system. + +This completes our tutorial, I hope it was simple enough to understand & learn. If you are having any issues or have have any queries, please mention them in the comment box below. + + +-------------------------------------------------------------------------------- + +via: http://linuxtechlab.com/create-swap-using-fdisk-fallocate/ + +作者：[Shusain][a] +译者：[lujun9972](https://github.com/lujun9972) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]:http://linuxtechlab.com/author/shsuain/ +[1]:https://i1.wp.com/linuxtechlab.com/wp-content/plugins/a3-lazy-load/assets/images/lazy_placeholder.gif?resize=668%2C211 +[2]:https://i0.wp.com/linuxtechlab.com/wp-content/uploads/2017/02/fidsk.jpg?resize=668%2C211 +[3]:https://i1.wp.com/linuxtechlab.com/wp-content/plugins/a3-lazy-load/assets/images/lazy_placeholder.gif?resize=620%2C157 +[4]:https://i0.wp.com/linuxtechlab.com/wp-content/uploads/2017/02/fidsk-swap-select.jpg?resize=620%2C157