6. Memory Management in CentOS 7

Apr 13, 2024#CentOS7学习笔记186

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Storage management in CentOS7 External storage: - Mobile storage devices: CD, USB drive - Fixed storage devices: Hard drive Using CD: Prepare CentOS7 installation CD Steps: 1. Insert ISO image into virtual machine CD drive 2. Create mount directory (recommended in media or mnt directory) 3. Mount CD to specified mount directory: mount device name usually under /dev mount directory 4. Access CD through mount directory 5. Unmount CD after use: umount device name or umount mount directory Using hard drive: Static disk (basic disk) Understanding partition types: - Primary partition: numbered 1-4 - Extended partition: numbered 1-4 - Logical partition: numbered greater than 5 Characteristics: - Primary + extended partitions <= 4 - 0 or 1 extended partition - Space in extended partition cannot be used directly, need to create logical partition on it - No limit on number of logical partitions Example: Partition (partition file: /dev/sdb) Subcommands for fdisk: n create partition, p view partition, w save partition, q exit partition Create file system (fat32, ext4): mkfs.ext4 Create mount directories: /mnt/disk1, /mnt/disk2, /mnt/disk3 Mount partition using mount command To make device permanently mounted, modify /etc/fstab file To make /etc/fstab file effective: - Restart system - Execute mount -a /etc/fstab file format: Device file Mount point File type Read/write mode (rw, ro) 0 0

Storage Management in CentOS7#

External Storage#

Mobile storage devices: CD, USB flash drive
Fixed storage devices: Hard drive

Using CD: Install CD (Prepare CentOS7 installation CD)#

Experimental Steps (Core Idea: Mounting)#

Insert the ISO image into the virtual machine's optical drive
Create a mounting directory (It is recommended to create the mounting directory under the media directory or mnt directory)
Mount the CD to the specified mounting directory: mount device name usually under /dev mounting directory
Access the mounting directory to access the CD
After use, you can unmount the CD:

umount device name
or
umount mounting directory

Using Hard Drive: Static Disk (Basic Disk)#

Knowledge Point: Understanding partition types

Primary partition: Numbered 1-4
Extended partition: Numbered 1-4
Logical partition: Numbered greater than 5

Characteristics:

Primary partition + Extended partition <= 4
0 or 1 Extended partition
The space of the Extended partition cannot be used directly. If you want to use it, you need to create a logical partition on it
The number of logical partitions is unlimited

For example:

Partition (Partition file: /dev/sdb)
Subcommands of fdisk: n create partition; p view partition, w save partition, q exit partition
Create file system (fat32, ext4): mkfs.ext4
Create mounting directories mnt/disk1; /mnt/disk2; /mnt/disk3
Use mount command to mount the partition

To check the mounted devices, simply enter mount

mount is "temporary": when the host restarts, the system automatically unmounts the device

How to make the device permanently mounted? Solution: Modify the configuration file /etc/fstab

How to make the /etc/fstab file take effect
Method one, restart the system
Method two, execute mount -a

Format of /etc/fstab file

Device file Mount point File type Read-write mode (rw,ro) 0 0