在windows操作系统中，硬盘有fat32和ntfs等多种格式。在linux中同样如此。CentOS 6之前，主要是ext4、ext3和ext2等格式。在CentOS 7这个版本开始，默认的磁盘格式变成了xfs格式。
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[root@server02 ~]# cat /etc/filesystems xfs ext4 ext3 ext2 nodev proc nodev devpts iso9660 vfat hfs hfsplus * [root@server02 ~]# mount //查看分区的文件系统类型，需要挂载才能看见 sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=494380k,nr_inodes=123595,mode=755) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu) cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_prio,net_cls) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) configfs on /sys/kernel/config type configfs (rw,relatime) /dev/sda3 on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota) selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=26,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) debugfs on /sys/kernel/debug type debugfs (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel) mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel) /dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota) tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=100840k,mode=700)
一、磁盘格式化
| 命令 | 参数 | 涵义 |
mke2fs | -t | 指定格式，不支持xfs； mkfs.ext4 = mke2fs -t ext4 |
| -b | 指定块大小 | |
| -m | 指定预留空间比（默认5%预留给超级用户） | |
| -i | 指定每组的inode数，默认4个块对应1个inode | |
| mkfs.xfs | 格式化成xfs |
测试示例：
[root@server02 ~]# mke2fs -t xfs /dev/sdb2 mke2fs 1.42.9 (28-Dec-2013) Your mke2fs.conf file does not define the xfs filesystem type. Aborting... [root@server02 ~]# mkfs.xfs /dev/sdb2 meta-data=/dev/sdb2 isize=512 agcount=4, agsize=131072 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=0, sparse=0 data = bsize=4096 blocks=524288, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal log bsize=4096 blocks=2560, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 [root@server02 ~]# blkid /dev/sdb2 /dev/sdb2: UUID="d1873a00-ba11-4635-81af-a1e9bd697f70" TYPE="xfs"
二、磁盘挂载
只有格式化的分区才能被挂载。挂载使用mount命令，卸载使用umount命令。使用“-o”可以跟各种选项。默认选项为rw,suid,dev,exec,auto,nouser,和async。
[root@server02 ~]# mount /dev/sdb2 /mnt/ [root@server02 ~]# mount /dev/sdb3 /mnt/ mount: /dev/sdb3 写保护，将以只读方式挂载 mount: 未知的文件系统类型“(null)” [root@server02 ~]# df -h 文件系统 容量 已用 可用 已用% 挂载点 /dev/sda3 28G 1016M 27G 4% / devtmpfs 483M 0 483M 0% /dev tmpfs 493M 0 493M 0% /dev/shm tmpfs 493M 6.8M 486M 2% /run tmpfs 493M 0 493M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 99M 0 99M 0% /run/user/0 /dev/sdb2 2.0G 33M 2.0G 2% /mnt [root@server02 ~]# umount /dev/sdb2 [root@server02 ~]# df -h 文件系统 容量 已用 可用 已用% 挂载点 /dev/sda3 28G 1016M 27G 4% / devtmpfs 483M 0 483M 0% /dev tmpfs 493M 0 493M 0% /dev/shm tmpfs 493M 6.8M 486M 2% /run tmpfs 493M 0 493M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 99M 0 99M 0% /run/user/0
通过mount命令挂载的分区只在当前有效，当系统重启之后，分区将会消失。将分区挂载卸载/etc/fstab文件中，可以使系统启动时默认挂载。可以使用mount -a命令自动加载配置文件里的配置。
[root@server02 ~]# cat /etc/fstab # # /etc/fstab # Created by anaconda on Sat May 27 06:10:33 2017 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=de480d95-018b-4e0b-a874-083a13d8412d / xfs defaults 0 0 UUID=82044aec-23c6-4e7f-8f05-51a24c0c956a /boot xfs defaults 0 0 UUID=be771427-d6c1-4d01-a8ab-a473e8df8ac5 swap swap defaults 0 0 [root@server02 ~]# man fstab ...... DESCRIPTION The file fstab contains descriptive information about the various file systems. fstab is only read by programs, and not written; it is the duty of the system administrator to properly create and maintain this file. Each filesystem is described on a separate line; fields on each line are separated by tabs or spaces. Lines starting with '#' are comments, blank lines are ignored. The order of records in fstab is important because fsck(8), mount(8), and umount(8) sequentially iterate through fstab doing their thing. The first field (fs_spec). //UUID或LABEL This field describes the block special device or remote filesystem to be mounted. ...... The second field (fs_file). //挂载点 This field describes the mount point for the filesystem. For swap partitions, this field should be specified as `none'. If the name of the mount point contains spaces these can be escaped as `\040'. ...... The third field (fs_vfstype). //分区格式 This field describes the type of the filesystem. Linux supports lots of filesystem types, such as adfs, affs, autofs, coda, coherent, cramfs, devpts, efs, ext2, ext3, hfs,hpfs, iso9660, jfs, minix, msdos, ncpfs, nfs, ntfs, proc, qnx4, reiserfs, romfs, smbfs, sysv, tmpfs, udf, ufs, umsdos, vfat, xenix, xfs, and possibly others. For more details, see mount(8). ...... The fourth field (fs_mntops). //可选选项 This field describes the mount options associated with the filesystem. ...... The fifth field (fs_freq). //是否备份 This field is used for these filesystems by the dump(8) command to determine which filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and dump will assume that the filesystem does not need to be dumped. ...... The sixth field (fs_passno). //是否开机检测，不检查为0，检查为2 This field is used by the fsck(8) program to determine the order in which filesystem checks are done at reboot time. The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno of 2. Filesystems within a drive will be checked sequentially, but filesystems on different drives will be checked at the same time to utilize parallelism available in the hardware. If the sixth field is not present or zero, a value of zero is returned and fsck will assume that the filesystem does not need to be checked.
另外一种开机自动挂载的方法是将mount命令写在/etc/rc.local里，开机自动执行挂载命令达到挂载的效果。
