Linux file system and Disk Management __linux

A new disk disc needs to be partitioned, formatted (creating a file system) and mounted before it can be used properly. There are two formats for partition tables on disks: MBR (Master Boot record) and GPT (GUID Partition table)

Mbr:

Also known as the main boot sector, is the computer after the boot access to the hard disk must read the first sector, that is, 0 cylinder 0 Head 1 sectors, MBR by Bootload (446 bytes), partition table (64 bytes), MBR end flag (2 bytes) A total of 512 bytes. The maximum 2TB partition is supported. The MBR-formatted partition table supports 3 primary partitions and one extended partition.

Gpt:

In order to support partitions with a capacity greater than 2TB, a GPT partitioning table is introduced, with maximum support for 18EB

FDISK: Disk Partitioning tool

Fdisk <disk>

D: Delete a partition

L: List the types of partitions supported by the system

M: Printing Help

N: Add a new partition

P: Print partition Table

Q: Do not save exit

W: Save exit

T: Change the partition ID

2. Partprobe (CentOS 5), Kpartx,partx (CentOS 6):

Partprobe <disk>: Notifies OS system of disk partition table changes

Partx-a <disk>: Increase disk partitions or read all disk partitions

Partx-l <disk>: List all partitions of the disk

KPARTX-AF <disk>: Force additional disk partition mappings

Kpartx-l <disk>: Listing increased disk partition mappings

3. MKE2FS, MKFS: Format disk (create file system EXT2,EXT3,EXT4)

MKE2FS the configuration file/etc/mke2fs.conf, use the default parameters loaded with this command.

MKE2FS = mkfs-t ext2 = mkfs.ext2

MKE2FS:

-T: File system type (ext2 |  ext3 | EXT4)

-j: Equivalent to-t ext3

-L Label: Set volume label

-B (1024 | 2048 | 4096): Specify block size

-I num:num bytes Reserve an Inode

-N num: Directly specify how many Inode to reserve

-N: Do not create file system, but show actions performed during creation

-I. Num:inode size

-M num: The percentage of space reserved for administrators, defaults to 5

-U uuid: Using a custom UUID

-C: Check for bad block on disk before creating file system

-F: Force file system creation

-G: Customize how many blocks each block-group has

-G: Number of custom Block-group

-O [^]feature: Specify partition attributes

Feature: (Default sparse_super,filetype,resize_inode,dir_index,ext_attr)

Dir_index: Use b-trees hash to speed up large directory queries.

Extend: Speed up large file system access (large files)

filetype: Storing file type information

FLEX_BG: Allow Block-group information to be placed anywhere in the block

Has_journal: Create ext3 log (same-j)

Journal_dev: Create an external ext3 log to replace the Ext2 file system

Large_file: File system supports files larger than 2G

Resize_inode: Provides space for block-group growth

Sparse_super: Create a file system containing Super-block backups

UNINIT_BG: Accelerated file system Creation (supported only under EXT4)

-Q: Used to silently perform formatting in scripts

# MKE2FS/DEV/SDB1

MKE2FS 1.41.12 (17-may-2010)

warning:252 blocks unused.

FileSystem label=

OS Type:linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, stripe width=0 blocks

328320 inodes, 1310720 blocks

65548 blocks (5.00%) reserved for the Super user

The Data block=0

Maximum filesystem blocks=1342177280

Block groups

32768 blocks per group, 32768 fragments per group

8208 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736

Writing Inode Tables:done

Writing superblocks and filesystem accounting Information:done

This filesystem would be automatically checked every mounts or

180 days, whichever comes. Use Tune2fs-c or-i to override.