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这些“主机”目录是什么？

tag-icon • tag-icon linux virtual-machine disk fdisk vmware-workstation
这些“主机”目录是什么？

我使用的是 Oracle Linux 7.6，它是基于 RHEL 7.6 的发行版。以下测试在 RHEL 7.6 或其他基于 RHEL 7.6 的发行版上应该是相同的。

我正在 Windows 10 上的 VMware Workstation 中运行 Oracle Linux 7.6 服务器。我想要做的是将磁盘添加到 Linux 来宾虚拟机，而无需重新启动 Linux 服务器。我用谷歌搜索了一下，发现了这个页面：https://rahsupport.wordpress.com/2017/08/10/vmware-add-disk-to-linux-without-rebooting-the-vm/。基本上，它的作用是：

  • 将 VMware Workstation 中的磁盘添加到 Linux 虚拟机
  • 去/sys/class/scsi_host/
  • 跑步echo '- - -' > host1/scan
  • 然后运行fdisk -l就可以看到新添加的磁盘

我在我的环境中对其进行了测试。存在三个这样的主机目录，每个目录scan中都有一个文件：

root:[/sys/class/scsi_host]# ls -la
total 0
drwxr-xr-x.  2 root root 0 Aug 24 22:49 .
drwxr-xr-x. 54 root root 0 Aug 24 22:49 ..
lrwxrwxrwx.  1 root root 0 Aug 24 22:49 host0 -> ../../devices/pci0000:00/0000:00:07.1/ata1/host0/scsi_host/host0
lrwxrwxrwx.  1 root root 0 Aug 24 22:49 host1 -> ../../devices/pci0000:00/0000:00:07.1/ata2/host1/scsi_host/host1
lrwxrwxrwx.  1 root root 0 Aug 24 22:49 host2 -> ../../devices/pci0000:00/0000:00:10.0/host2/scsi_host/host2
root:[/sys/class/scsi_host]#
root:[/sys/class/scsi_host]# ls -la */scan
--w-------. 1 root root 4096 Aug 24 22:50 host0/scan
--w-------. 1 root root 4096 Aug 24 22:50 host1/scan
--w-------. 1 root root 4096 Aug 24 22:50 host2/scan
root:[/sys/class/scsi_host]#

本来Linux服务器无法识别磁盘：

root:[/sys/class/scsi_host]# fdisk -l

Disk /dev/sda: 1099.5 GB, 1099511627776 bytes, 2147483648 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 label type: dos
Disk identifier: 0x000d3e78

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896  2059401215  1029212160   83  Linux
/dev/sda3      2059401216  2101344255    20971520   83  Linux
/dev/sda4      2101344256  2147483647    23069696    5  Extended
/dev/sda5      2101348352  2143289343    20970496   83  Linux
/dev/sda6      2143291392  2147483647     2096128   82  Linux swap / Solaris

但是当我运行时echo '- - -' > host0/scan，磁盘出现了：

root:[/sys/class/scsi_host]# echo '- - -' > host0/scan
root:[/sys/class/scsi_host]# fdisk -l

Disk /dev/sda: 1099.5 GB, 1099511627776 bytes, 2147483648 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 label type: dos
Disk identifier: 0x000d3e78

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896  2059401215  1029212160   83  Linux
/dev/sda3      2059401216  2101344255    20971520   83  Linux
/dev/sda4      2101344256  2147483647    23069696    5  Extended
/dev/sda5      2101348352  2143289343    20970496   83  Linux
/dev/sda6      2143291392  2147483647     2096128   82  Linux swap / Solaris

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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

root:[/sys/class/scsi_host]#

我将 Linux VM 恢复到原始状态以再次测试。这次它表明echo '- - -' > host1/scan不起作用，但echo '- - -' > host2/scan有效。

root:[/sys/class/scsi_host]# fdisk -l

Disk /dev/sda: 1099.5 GB, 1099511627776 bytes, 2147483648 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 label type: dos
Disk identifier: 0x000d3e78

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896  2059401215  1029212160   83  Linux
/dev/sda3      2059401216  2101344255    20971520   83  Linux
/dev/sda4      2101344256  2147483647    23069696    5  Extended
/dev/sda5      2101348352  2143289343    20970496   83  Linux
/dev/sda6      2143291392  2147483647     2096128   82  Linux swap / Solaris
root:[/sys/class/scsi_host]# echo '- - -' > host1/scan
root:[/sys/class/scsi_host]# fdisk -l

Disk /dev/sda: 1099.5 GB, 1099511627776 bytes, 2147483648 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 label type: dos
Disk identifier: 0x000d3e78

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896  2059401215  1029212160   83  Linux
/dev/sda3      2059401216  2101344255    20971520   83  Linux
/dev/sda4      2101344256  2147483647    23069696    5  Extended
/dev/sda5      2101348352  2143289343    20970496   83  Linux
/dev/sda6      2143291392  2147483647     2096128   82  Linux swap / Solaris
root:[/sys/class/scsi_host]# echo '- - -' > host2/scan
root:[/sys/class/scsi_host]# fdisk -l

Disk /dev/sda: 1099.5 GB, 1099511627776 bytes, 2147483648 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 label type: dos
Disk identifier: 0x000d3e78

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896  2059401215  1029212160   83  Linux
/dev/sda3      2059401216  2101344255    20971520   83  Linux
/dev/sda4      2101344256  2147483647    23069696    5  Extended
/dev/sda5      2101348352  2143289343    20970496   83  Linux
/dev/sda6      2143291392  2147483647     2096128   82  Linux swap / Solaris

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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

root:[/sys/class/scsi_host]#

我的问题是，这些是什么主持人目录？为什么echo '- - -' > host0/scan会让echo '- - -' > host2/scanLinux服务器识别磁盘，但echo '- - -' > host1/scan不能呢？

顺便说一句，我对 Linux 还很陌生，仍在学习中。

答案1

不同的host目录对应不同的磁盘控制器。控制器映射到什么取决于所涉及的技术； AHCI SATA 主机每个端口一台主机，NVMe 每个控制器使用一台主机，等等。具体情况取决于您的虚拟机设置。

基本上这意味着您应该重新扫描所有主机。

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