Shulou(Shulou.com)06/03 Report--

1. The file system is based on partitions and can be seen as an application that organizes and manages files.

The file storage structure of ext2 is as follows:

Boot block + Block Group 1 + Block Group 2 + Block Group 3 +.

The block group structure is shown in the following figure:

It is composed of super block group, GDT block group description table, inode bitmap, block bitmap, inode table and data block.

2. Ext2 is divided into data area and metadata area.

Ext3 is divided into data area, metadata area and log area.

Ext3 belongs to the log file system. When writing data, it first writes to the log area, and then writes to the data area from the log area. This file type can accurately locate the abnormal location in the event of a sudden power outage and other abnormal conditions, and speed up the repair of the file system. The cost is that the speed of writing data is slower than that of ext2, and there is no effect when reading data.

3. Some operation commands of file partition

Fdisk-l: check the partition status

Fdisk / dev/sda: operate on the / dev/sda partition. The following operations are carried out on this basis.

M View help

P View

N New partition

D delete partition

T modify partition type

Q exit does not save

W Save and exit

4. After the partition is created, the configuration will not be written to the kernel immediately. You can use cat / proc/partitions to view the configuration in the kernel. If it is inconsistent, you can use the partprobe / dev/sda command to notify the kernel of the partition table changes.

5. The number of blocks contained in each block group is determined by the size of the block, because the block bitmap exists in a block, each block occupies a bit (0 indicates that it is not used, 1 indicates that it has been used). If the block size is 1024 bytes, the maximum number of blocks contained in the block group is 10248-8192, and if the block size is 2048 bytes, the maximum number of blocks in the block group is 20488-16384

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