Linux Disk Management with Margo Linux (Lesson 4)

Linux File System Management:

MKFS, Mkfs-type = mkfs.ext2,3,4

Cases:

[[email protected] ~]# mkfs -type ext4 /dev/sdbmkfs.ype: no such  File or directory[[email protected] ~]# mkfs -t ext4 /dev/sdbmke2fs  1.41.12  (17-may-2010)/dev/sdb is entire device, not just one  partition! proceed anyway?  (y,n)  yFilesystem label=OS type: LinuxBlock size=4096  (log=2) fragment size=4096  (log=2) stride=0 blocks, stripe width=0 blocks1310720  inodes, 5242880 blocks262144 blocks  (5.00%)  reserved for the super  userFirst data block=0Maximum filesystem blocks=4294967296160 block  Groups32768 blocks per group, 32768 fragments per group8192 inodes  per groupSuperblock backups stored on blocks: 32768, 98304,  163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000writing inode tables : done                             Creating journal  (32768  blocks):  donewriting superblocks and filesystem accounting information:  doneThis filesystem will be automatically checked every 25  Mounts or180 days, whichever comes first.  use tune2fs -c or  -i to override.

Ext:mke2fs

Cases:

[[email protected] ~]# mkfs.ext4 /dev/sdbmke2fs 1.41.12  (17-May-2010)/dev/sdb  is entire device, not just one partition! proceed anyway?  (y,n)  yFilesystem label=OS type: LinuxBlock size=4096  (log=2) fragment size=4096  (log=2) stride=0 blocks, stripe width=0 blocks1310720  inodes, 5242880 blocks262144 blocks  (5.00%)  reserved for the super  userFirst data block=0Maximum filesystem blocks=4294967296160 block  Groups32768 blocks per group, 32768 fragments per group8192 inodes  per groupSuperblock backups stored on blocks: 32768, 98304,  163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000writing  inode tables: done                             Creating journal  (32768 blocks): donewriting  Superblocks and filesystem accounting information: donethis filesystem will  be automatically checked every 37 mounts or180 days, whichever  comes first.  use tune2fs -c or -i to override.

Creating a file system

MKE2FS [OPTION]: DEVICE

-T EXT2,EXT3,EXT4

-B 1024,2048,4096

-l ' lable ' label

-j MKE2FS-T Ext

-I. Inode

-N Reserved how many inode

-M reserves the percentage of disk space for post-management

-O feature[...] Turn on reserved features

-o^featuew[...] Turn off reserved features

File System Properties View and adjustment tools:

E2lable: Managing File System Volume labels

E2lable DEVICE [Lavle]

Cases:

[Email protected] ~]# e2label/dev/sdb ' mydisk ' [[email protected] ~]# E2label/dev/sdb

Mydisk

TUNE2FS: Display file System Properties, or adjust file system Properties

-L Display superblock information

-l lable Modifying the volume label

-m manage reserved space for administrators

-j EXT2-->EXT3

-O Enable or disable attributes

-o File system default mount option turned on or off

Example 1:

[[email protected] ~]# tune2fs -l /dev/sdbtune2fs 1.41.12  (17-May-2010) filesystem volume name:   mydisklast mounted on:           <not available>Filesystem UUID:           e2ec1086-064d-4eac-950f-0672a508213efilesystem magic number:   0xEF53Filesystem revision #:    1  (dynamic) filesystem  features:      has_journal ext_attr resize_inode dir_index  Filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_ Nlink extra_isizefilesystem flags:         signed_ directory_hash default mount options:     (None) Filesystem state:          cleanerrors behavior:           continuefilesystem os type:       linuxinode count:               1310720Block count:               5242880Reserved block  count:     262144free blocks:               5116591Free inodes:               1310709First block:               0Block size:                4096Fragment size:             4096reserved  gdt blocks:      1022blocks per group:          32768Fragments per group:       32768inodes per group:         8192inode blocks  per group:   512Flex block group size:     16filesystem created:       sun sep  6 19:08:01  2015Last mount time:          n/aLast  write time:          sun sep  6  19:10:29 2015mount count:               0Maximum mount count:      37Last checked:              sun sep  6 19:08:01 2015check interval:            15552000  (6 months) Next check after:          Fri Mar  4 19:08:01  2016lifetime writes:          452 mbreserved  blocks uid:      0  (user root) Reserved blocks gid:       0  (group root) first inode:               11Inode size:           256required extra isize:     28desired extra  isize:      28Journal inode:             8default directory hash:   half_md4directory hash seed:       4fc68caf-3b7f-401e-8022-707100c2b923Journal backup:            inode blocks

DUMPE2FS display file system layout and superblock information

Cases:

Dumpe2fs/dev/sdb

File System Detection System

FSCK File System Detection

Fsck-t test = Fsck.type

-A automatically fix file system errors

-F Interactive Repair

-F Force Detection

Cases:

[Email protected] ~]# fsck.ext4-a/dev/sdb Mydisk:clean, 11/1310720 files, 126289/5242880 blocks

E2fsck:ext File System Special Detection Tool

-Y auto Fix error

-F Force Detection

Cases:

[Email protected] ~]# e2fsck-f/dev/sdbe2fsck 1.41.12 (17-may-2010) Pass 1:checking inodes, blocks, and Sizespass 2:che cking directory structurepass 3:checking directory connectivitypass 4:checking reference countspass 5:checking group Su Mmary informationmydisk:11/1310720 files (0.0% non-contiguous), 126289/5242880 blocks

File system mount and use

Kernel--ROOTFS partition

ROOTFS partition

Bin,sbin,boot,etc,lib,lib64,dev,tmp,usr,proc

Establish an association between the additional file system and a pre-asked directory of the root filesystem, making this directory the gateway to the other directory, becoming a mount

The process of contacting this association, called unloading

Mount points: mount point device mounts to this directory

Note: Mount points need to be empty directories

Mount Method: Mount: Reads the/etc/mtab file to display all the current system

Mount-a Mount/etc/fstab All devices that support automatic mounting in the volume file

Mount [OPTION] [-o-option] DEVICE Mount_point

[option] Command options

[-o option] hangs on options

Device: Devices to be mounted

(1) Device file:/DEV/SDA

(2) Volume label-l

(3) Uuid-u

(4) Pseudo file System file name mount

Common options

-T File System Properties

-R mount in read-only mode

-W Mount in read-write mode

-N Each file system is automatically updated when mounted/etc/mtab-n disable this feature

-A automatically mounts all devices that support automatic mounting

-B Bind directory to another directory

Cases:

[Email protected] ~]# mkdir/mydata[[email protected] ~]# mount-o rw,async,noatime/dev/sdb/mydata

-O mount option

Async Async Mode

Sync Sync mode

Atime/noatime whether to update the access timestamp

Diratime/nodiratime whether to update access directory timestamp

Auto/noauto whether this device is allowed to mount automatically

Exec/noexec whether executable programs on this file system are allowed to execute

Dev/nodev support for using device files on this device

Suid/nosudi

Remount Re-mount

Ro/rw

User/nouser whether a normal user is allowed to mount this device

Whether the ACL allows this device to use Facl

Umount: Uninstall command

Umount DEVICE

Umount Mount_point

Cases:

[Email protected] ~]# umount/dev/sdb[[email protected] ~]# Umount/mydata

To view the process that is accessing the specified mount point

Fuser-v Mount_point

Terminates all processes that are accessing the specified mount point

fuser-km Mount_point

Cases:

[[email protected] ~]# fuser-v/mydata USER PID ACCESS command/mydata:root 2476.. C.. bash[[email protected] ~]# fuser-km/mydata/mydata:2476c

Swap partition:

Free command

View menmory and Swap usage status

Free-m shown in MB

Cases:

[[email protected] ~]# free -m               total       used        free     shared    buffers      cachedMem:          1862         253       1609           0         51          63-/+ buffers/cache:        137        1724 swap:         3071           0       3071

Free-g with G display (4 5 in Display)

Cases:

[[email protected] ~]# free -g              total       used        free     shared    buffers      cachedmem:             1           0          1           0           0          0-/+ buffers/cache:           0          1  swap:            2          &Nbsp;0          2 

Practice:

Create a 10G file system, type EXT4, require boot to automatically mount to/mydata directory

[[email protected] ~]# fdisk -l /dev/sdbdisk /dev/sdb: 21.5 gb,  21474836480 bytes255 heads, 63 sectors/track, 2610 cylindersunits =  cylinders of 16065 * 512 = 8225280 bytessector size  (logical/ Physical): 512 bytes / 512 bytesi/o size  (minimum/optimal): 512  bytes / 512 bytesdisk identifier: 0x13a6c9bf   device boot       Start         End       Blocks   Id  System/dev/sdb1                1        1306     10490413+  83  linux[[email protected] fs]# kpartx  -a /dev/sdb1[[email protected] fs]# mkfs.ext4 /dev/sdb1mke2fs 1.41.12  (17-May-2010) Filesystem  label=OS type: LinuxBlock size=4096  (log=2) fragment size=4096  (log=2) stride=0 blocks, stripe width=0 blocks655776 inodes, 2622603 blocks131130  blocks  (5.00%)  reserved for the super userfirst data block= 0maximum filesystem blocks=268854886481 block groups32768 blocks per group,  32768 fragments per group8096 inodes per groupsuperblock backups  STORED ON BLOCKS: 32768, 98304, 163840, 229376, 294912, 819200,  884736, 1605632Writing inode tables: done                              creating journal  (32768 blocks):  donewriting superblocks and filesystem accounting  information: donethis filesystem will be automatically checked every  39 mounts or180 days, whichever comes first.  use tune2fs  -c or -i to override. [[email protected] fs]# e2label /dev/sdb1  ' MyData ' [[email protected] fs]#  E2LABEL /DEV/SDB1MYDATA[[EMAIL PROTECTED] FS] #vim  /etc/fstabLABEL=mydata                   /mydata                  ext4     defaults        0 0

Linux Disk Management with Margo Linux (Lesson 4)