linux中Centos7增加swap分区详解
<div id="navCategory"><h5 class="catalogue">目录</h5><ul class="first_class_ul"><li>方法一、</li><li>
方法二、</li></ul></div><p>
<strong>注意：（Redhat5官方推荐）</strong></p>
<p>
RAM<=4G,swap=2G;RAM>4G,<16G,swap=4G;RAM>16G,<64G,swap=8G;RAM>64G,<256G,swap=16G</p>
<p>
（Redhat6/7官方推荐）RAM<=2G,swap=2*RAM;RAM>2G,<8G,swap=RAM;RAM>8G,<64G,swap>=4G;RAM>=64G,swap>=4G;（休眠状态另外考虑）</p>
<p>
添加swap有两种方式：1、添加swap分区；2、添加swap文件；</p>
<p class="maodian"></p><h2>
方法一、</h2>
<p>
添加swap空间可用于解决系统物理内存占用过高，导致部分服务被强制关闭的问题</p>
<p>
在关机状态下，添加一块200M（0.2G）的硬盘</p>
<p>
查看swap大小</p>
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<code class="xhtml plain">free -m //或者 cat /proc/meminfo | grep -i swap 或者 fdisk -l 或者swap -s</code>
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查看新添加的硬盘 这里新添加的磁盘是sdb（看容量可知）</p>
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<code class="xhtml plain">cat /proc/partitions</code>
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<p>
创建分区 并设置为swap格式</p>
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<code class="xhtml plain">fdisk /dev/sdb</code>
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<code class="xhtml plain">n //创建分区 </code>
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<code class="xhtml plain">p //创建主分区 </code>
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<code class="xhtml plain">1 //创建分区1 </code>
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<code class="xhtml plain">两次回车 //起始扇区和Last扇区选择默认</code>
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<code class="xhtml plain">t //转换分区格式 </code>
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<code class="xhtml plain">82 //转换为swap空间 </code>
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<code class="xhtml plain">p //查看已创建的分区结果 </code>
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<code class="xhtml plain">w //保存退出</code>
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格式化为swap空间</p>
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<code class="xhtml plain">mkswap /dev/sdb1</code>
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启用swap</p>
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<code class="xhtml plain">swapon /dev/sdb1</code>
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编辑配置文件 设为开机自动挂载</p>
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<code class="xhtml plain">vim /etc/fstab</code>
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添加以下内容 保存并退出</p>
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<code class="xhtml plain">/dev/sdb1 swap swap defaults 0 0</code>
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设置自动启用所有swap空间</p>
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<code class="xhtml plain">swapon -a</code>
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重启验证</p>
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<code class="xhtml plain">reboot</code>
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再次查看swap大小</p>
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<code class="xhtml plain">free -m //或者 cat /proc/meminfo | grep -i swap 或者 fdisk -l 或者swap -s</code>
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注意：可以看出来swap已经发生变化了</p>
<p class="maodian"></p><h2>
方法二、</h2>
<p>
添加swap空间可用于解决系统物理内存不够，导致部分服务被强制关闭的问题</p>
<p>
查看swap大小</p>
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<code class="xhtml plain">free -m //或者 cat /proc/meminfo | grep -i swap 或者 fdisk -l 或者swap -s</code>
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注意：如swap显示0，或者没有输出swap，则表示系统并没有增加swap空间</p>
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创建swap文件</p>
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<code class="xhtml plain">fallocate -l 2G /etc/swap //指定文件为2G</code>
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设置只允许root用户操作该文件</p>
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<code class="xhtml plain">chmod 600 /etc/swap</code>
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检查文件大小与权限</p>
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<code class="xhtml plain">ls -lh /etc/swap</code>
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设置该文件为swap文件</p>
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<code class="xhtml plain">mkswap /etc/swap</code>
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启用swap文件</p>
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<code class="xhtml plain">swapon /etc/swap</code>
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使swap文件永久生效</p>
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<code class="xhtml plain">vim /etc/fstab</code>
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末尾添加：</p>
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<code class="xhtml plain">/etc/swap swap swap defaults 0 0</code>
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<p>
更改swap配置</p>
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<code class="xhtml plain">vim /etc/sysctl.conf</code>
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有则修改，无则添加：（按需修改数值）</p>
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<code class="xhtml plain">vm.swappiness=30 //值越大表示越倾向于使用swap空间</code>
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重启生效</p>
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<code class="xhtml plain">reboot</code>
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再次查看swap大小</p>
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<code class="xhtml plain">free -m //或者 cat /proc/meminfo | grep -i swap 或者 fdisk -l 或者swap -s</code>
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<p>
以上就是本次小编整理的全部内容，感谢大家对服务器之家的支持。</p>
<p>
原文链接：https://www.idaobin.com/archives/153.html</p>
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