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了解磁盘空间分区

tag-icon • tag-icon partitioning mount hard-drive
了解磁盘空间分区

我有一台装有 Ubuntu Server 18.04（256 RAM、2x 240 GB SSD）的专用服务器，现在的磁盘空间分配情况如下：

Filesystem      Size  Used Avail Use% Mounted on
udev            126G     0  126G   0% /dev
tmpfs            26G  1.7M   26G   1% /run
/dev/md2        219G  145G   64G  70% /
tmpfs           126G   12K  126G   1% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           126G     0  126G   0% /sys/fs/cgroup
/dev/loop0       90M   90M     0 100% /snap/core/7917
/dev/loop1      8.7M  8.7M     0 100% /snap/canonical-livepatch/88
/dev/md1        487M  146M  312M  32% /boot
tmpfs            26G     0   26G   0% /run/user/1000

Disk /dev/loop0: 89.1 MiB, 93454336 bytes, 182528 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop1: 8.5 MiB, 8941568 bytes, 17464 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe5bc9ccf

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sda1  *         4096   1050623   1046528   511M fd Linux raid autodetect
/dev/sda2         1050624 467808255 466757632 222.6G fd Linux raid autodetect
/dev/sda3       467808256 468854783   1046528   511M 82 Linux swap / Solaris


Disk /dev/sdb: 223.6 GiB, 240057409536 bytes, 468862128 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xd0864b40

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sdb1  *         4096   1050623   1046528   511M fd Linux raid autodetect
/dev/sdb2         1050624 467808255 466757632 222.6G fd Linux raid autodetect
/dev/sdb3       467808256 468854783   1046528   511M 82 Linux swap / Solaris


Disk /dev/md1: 511 MiB, 535756800 bytes, 1046400 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/md2: 222.6 GiB, 238979842048 bytes, 466757504 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

我有点困惑，因为显示的设备名称df -h与 中的不匹配fdisk -l。目前，我只能访问 1 个 SSD（/dev/md2），我不明白第二个 SSD 的用途，以及是否（以及如何）可以使用其上的磁盘空间。

答案1

您正在使用带有两个镜像硬盘（sda 和 sdb）的 RAID1 系统。其中fdisk -l显示了实际的物理磁盘及其分区，df -h显示了系统使用的 RAID 设备和分区。

即由和/dev/md1组成，两者内容相同。如果其中一个驱动器发生故障，数据在另一个驱动器上是安全的。/dev/sda1/dev/sdb1

要获取有关 raid 设备的更多详细信息，请使用mdadm（假设是通过此方法完成的）：

mdadm --detail /dev/md1

答案2

根据man df：

If  no file name is given, the space available on all
currently mounted file systems is shown.

并且man fdisk：

-l, --list
    List the partition tables for the specified devices and then exit. If  no  devices are given, 
those mentioned in /proc/partitions (if that file exists) are used.

所以不同之处df在于安装systems while fdisk -l（不带参数）显示以下列出的分区/proc/partitions

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