CIS 191 - Lesson 10

Lesson 10Skills Needed

• Create and configure filesystems

• Mount a filesystem

• Automatically mount filesystems on reboots

• Check and repair a filesystem

• Show disk usage information

• Set quotas on a file system

CIS 191 - Lesson 9

Partition Boot Sector

Data

Master Boot Record (MBR)

Partition Boot Sector

Data

Partition Boot Sector

Data

Partition Boot Sector

Data

Unused Boot Sector

Data

Unused Boot Sector

Making a file system

Superblock

Inode Table

ext2 file system

Data Blocks

mkfs –t ext2 /dev/sda3

CIS 191 - Lesson 9

Making File Systems

Superblock

Inode Table

Data Blocks

Analogy: making a file system on an empty partition is like painting the stripes on a parking lot. It organizes the space and makes it efficient.

ext2 file system

CIS 191 - Lesson 9

ext2 Filesystems

CIS 191 - Lesson 9

The ext2 filesystemBackground

• Original UNIX File System (UFS)• Bootstrap block • Superblock • Cylinder groups

• inodes (indexes)• data blocks• cylinder group header• backup copies of superblock

• The Fast File System (FFS) from BSD• Intended to overcome file fragment problems• Localize data associated data in cylinders to avoid head

thrashing• Put "last" bits of several files in single block

• ext2 takes some features of FFS and UFS• ext3 adds journaling

CIS 191 - Lesson 9

• FFS, ext2 Filesystems limit this with cylinder, and block groups

• ext2 File Systems tend to have little file fragmentation

• Largest contiguous ext2 file limited by block size and block/inode ratio

• Defragmenting an ext2 File System• Usually not enough fragmentation to use

defragmentation in ext2 • May be bugs in defragmenter

The ext2 filesystemFragmentation

CIS 191 - Lesson 9

Superblock

Inode Table

Data Blocks

ext2 file system

ext2 file system

Superblock has:• File system type, label, inode count, block

count, etc. about entire file system.• Redundant copies are maintained.• Use: dumpe2fs –h /dev/sda2 to see / superblock info

inodes have:• file type, permissions, link count, owner,

group, size, major and minor numbers, creation date, modification date, access date, pointers to data blocks.

• Does not contain filenames which are kept in directories.

• Use stat command to see inode information

Data blocks have actual file and directory data.

CIS 191 - Lesson 9

Superblock

Inode Table

ext2 file system

Data Blocks

[simmsben@opus ~]$ls -il letter102609 -rw-r--r-- 1 simmsben cis90 1044 Jul 20 2001 letter

Hello Mother! Hello Father!

Here I am at Camp Granada. Things are very entertaining,and they say we'll have some fun when it stops raining.

All the counselors hate the waiters, and the lake hasalligators. You remember Leonard Skinner? He gotptomaine poisoning last night after dinner.

Now I don't want this to scare you, but my bunk mate hasmalaria. You remember Jeffrey Hardy? Their about toorganize a searching party.

Take me home, oh Mother, Father, take me home! I hate Granada.Don't leave me out in the forest where I might get eatenby a bear! Take me home, I promise that I won't make noise,or mess the house with other boys, oh please don't make mestay -- I've been here one whole day.

Dearest Father, darling Mother, how's my precious littlebrother? I will come home if you miss me. I will evenlet Aunt Bertha hug and kiss me!

Wait a minute! It's stopped hailing! Guys are swimming!Guys are sailing! Playing baseball, gee that's better!Mother, Father, kindly disregard this letter.

Alan Sherman

bigfile 102574bin 102575letter 102609

bigfile 102574bin 102575letter 102609

102609

-

1

simmsben

cis90

1044

2001-07-20

2008-08-08

2008-06-20

Pointer(s) to data blocks

inode number

Type

Number of links

User

Group

Size

Modification time

Access Time

Change time

Pointer(s) to data blocks

rw-r—r-- Permissions

CIS 191 - Lesson 9

The ext2 filesystemData Blocks

CIS 191 - Lesson 9

Partition Boot Sector

Data

Master Boot Record (MBR)

Partition Boot Sector

Data

Partition Boot Sector

Data

Partition Boot Sector

Data

Unused Boot Sector

Data

Unused Boot Sector

Making a file system

Superblock

Inode Table

ext2 file system

Data Blocks

mkfs –t ext2 /dev/sda3

CIS 191 - Lesson 9

mkfs –t type device -t ext2 –t ext3 (has journaling) -t vfat (compatible with Windows) -t jfs (IBM’s journaled file system) -t reiserfs

For ext2 or ext3 use: -N option to specify number of inodes-m option to specify % blocks reserved for superuser (default 5%)-L option to set the volume label for the file system

Example: mkfs –t ext3 /dev/sda6(puts ext3 file system on 6th partition of 1st SCSI drive)

Example: mkfs –t ext2 –m 0 –N 1000 –L myfiles /dev/sda6(puts ext2 file system with 1000 inodes, no space reserved for superuser, volume label “myfiles” on 6th partition of 1st SCSI drive, )

Note: mkfs is actually a front end for various filesystem builders.

[root@rh9 root]# ls /sbin/mkfs*/sbin/mkfs /sbin/mkfs.ext2 /sbin/mkfs.jfs /sbin/mkfs.reiserfs/sbin/mkfs.cramfs /sbin/mkfs.ext3 /sbin/mkfs.msdos /sbin/mkfs.vfat

mkfs command

Use man mke2fs to see all options

CIS 191 - Lesson 9

FYIMaking a file system in a file

Superblock

Inode Table

Data Blocks

Superblock

Inode Table

Data Blocks

Yes, believe it or not, this can be done too

CIS 191 - Lesson 9

FYIMaking a file system in a file

Yes, believe it or not, this can be done too

CIS 191 - Lesson 9

FYIMaking a file system in a file

Yes, believe it or not, this can be done too

CIS 191 - Lesson 9

ManageFilesystems

CIS 191 - Lesson 9

File Systemsext2 filesystem utilities

[root@benji bin]# ls /sbin/*fs*/sbin/debugfs /sbin/fsck.ext2 /sbin/mkfs.cramfs /sbin/resize2fs/sbin/dosfsck /sbin/fsck.ext3 /sbin/mkfs.ext2 /sbin/tune2fs/sbin/dosfslabel /sbin/fsck.msdos /sbin/mkfs.ext3 /sbin/umount.cifs/sbin/dumpe2fs /sbin/fsck.vfat /sbin/mkfs.msdos /sbin/umount.nfs/sbin/e2fsck /sbin/fstab-decode /sbin/mkfs.vfat /sbin/umount.nfs4/sbin/findfs /sbin/mkdosfs /sbin/mount.cifs/sbin/fsck /sbin/mke2fs /sbin/mount.nfs/sbin/fsck.cramfs /sbin/mkfs /sbin/mount.nfs4[root@benji bin]#

CIS 191 - Lesson 9

File SystemsFile System Creation

mkfs.ext2 (mke2fs)• Creates Linux ext2 file systems

mklost+found• Creates lost and found directory on mounted ext2 file

systemsresize2fs

• Resize an ext2 file systeme2label

• Used to change or view label of ext2 file system

CIS 191 - Lesson 9

File SystemsFile System Manipulation

debugfs/dumpe2fs• File system debugger • Most dangerous and powerful of e2fsprogs

tune2fs• Adjusts file system parameters

uuidgen• Creates universally unique identities

CIS 191 - Lesson 9

ext2 file systemUsing dumpe2fs –h to show superblock information

If you leave off the –h option you will also see the data block status as well.

Superblock

Inode Table

Data Blocks

CIS 191 - Lesson 9

ext2 file systemUsing stat command to show inode details

Note: The name of the file is not kept in the Inode. It is kept as data in a directory file.

Superblock

Inode Table

Data Blocks

CIS 191 - Lesson 9

Moving Files to New Partitions(with cp command)

When copying a directory like /home to another partition use options that don't follow symbolic links, preserve timestamps and are recursive

CIS 191 - Lesson 9

This is another way to do the same thing using tar command, () to run as a sub-shell so pwd is not changed and using – as a way to pipe stdout to another tar command for extraction

tar output shrunk

mkfs output shrunk

Moving Files to New Partitions(with tar command)

You will do this in Lab 7

CIS 191 - Lesson 9

Extended Propertieschattr and lsattr

chattr [-RV] [ + | - | = ] attribute

-R = recursive-V = verboseattributes: A = Don't update access time a = append mode only c = file gets compressed d = not backed up by dump i = immutable u = contents saved when deleted

lsattr• Lists the ext2 file system's extended permissions

CIS 191 - Lesson 9

With A set, access time is not changed when file is accessed

Extended Propertieschattr and lsattr

CIS 191 - Lesson 9

With A removed, access time is updated normally

Extended Propertieschattr and lsattr

CIS 191 - Lesson 9

With i (immutable) set, the file cannot be modified

Extended Propertieschattr and lsattr

CIS 191 - Lesson 9

With a (append only) set, the file can only be appended to

Extended Propertieschattr and lsattr

CIS 191 - Lesson 9

Check andRepair

CIS 191 - Lesson 9

Checking and RepairingWhat can cause corruption

Causes• Sudden loss of power in power failure • User switching off power improperly • Crash due to kernel or software • Program working on many files crashes

Shows up as:• Unreferenced inodes• Inexplicably large link counts• Unused data blocks not listed in block maps• Bad superblock summary information• Many files using one data block • Data blocks marked as free but being used (and

vice-versa)

CIS 191 - Lesson 9

Checking and RepairingCheck and repair tools

fsck• Front end for various file checking and repairing tools. • Used to check or repair file systems• Defaults to checking filesystems in /etc/fstab using the 6th

field for sequencing the checks• Runs during startup (see /etc/rc.d/rc.sysinit)• Runs much faster when checking ext3 (journaled) file

systems

badblocks• Searches block devices for bad blocks

CIS 191 - Lesson 9

Checking and Repairingfsck - File System Consistency Check

At startup Linux will check any filesystems that were dirty (not un-mounted cleanly)

As a precaution, filesystems are checked every random number of mounts. This number is shown when you created the filesystem:

This filesystem will be automatically checked every 31 mounts or180 days, whichever comes first. Use tune2fs -c or -i to override.[root@benji ~]#

This number can be modified using the tune2fs command with the –c option. Example from Lab 7 follows:

tune2fs –c 20 /dev/sda7

CIS 191 - Lesson 9

FYI: If you run fsck without any options or arguments it will cycle through /etc/fstab

Follow the advice here and don’t check an active filesystem

Checking and Repairing[root@benji ~]# fsckfsck 1.39 (29-May-2006)e2fsck 1.39 (29-May-2006)/dev/sda1 is mounted.

WARNING!!! Running e2fsck on a mounted filesystem may causeSEVERE filesystem damage.

Do you really want to continue (y/n)? no

check aborted.e2fsck 1.39 (29-May-2006)/dev/sda5 is mounted.

WARNING!!! Running e2fsck on a mounted filesystem may causeSEVERE filesystem damage.

Do you really want to continue (y/n)? no

check aborted.e2fsck 1.39 (29-May-2006)/dev/sda3 is mounted.

WARNING!!! Running e2fsck on a mounted filesystem may causeSEVERE filesystem damage.

Do you really want to continue (y/n)? no

check aborted.[root@benji ~]#

CIS 191 - Lesson 9

You may need to shut down services and change to run level 1 so you can un-mount the filesystem to check it.

Clean, so not checked

-f option forces the check to happen

Checking and RepairingForcing a check on a clean filesystem

CIS 191 - Lesson 9

Checking and Reparinglost+found directory

Note: The lost+found directory is created when you make a ext2 or ext3 file system.

This is where the fsck utility will place any recovered data it finds when checking a file system.

Don’t delete it!

CIS 191 - Lesson 9

Mounting Filesystems

CIS 191 - Lesson 9

Mounting and Un-mounting file systems • mount [device-file] [directory] • umount [device-file | directory]

Mount information1./etc/fstab (what to mount at boot time)2./etc/mtab (current mount status)

Mounting File Systems

CIS 191 - Lesson 9

/

/bin

/etc

/mnt

/cdrom

On the rh9 VM

/dev

/boot

/home

/rsimms

/grub

/lost+found

/lost+found

/dev/sda1

/dev/sda2

/dev/sda5

/dev/sda6

/floppy

/hgfs

mount command with no arguments shows current mount status in /etc/mtab

Showing current mount status

CIS 191 - Lesson 9

/

/bin

/etc

/mnt

/dir1

On the rh9 VM

/dev

/boot

/home

/rsimms

/grub

/lost+found

/lost+found

/fdir2

/lost+found

mount will overlay the new filesystem on a directory in the current file hierarchy. The old directory is no longer accessible until the new one is un-mounted

Making a file system and mounting it

/

/bin /etc /mnt

/cdrom

/dev/boot /home

/rsimms

/grub

/lost+found

/lost+found

/floppy

/hgfs

/lib

/dev/sda6

/dev/sda1

/dev/sda5

Mounting File SystemsLike pinning the tail on the donkey

mount /dev/sda6 /mnt

CIS 191 - Lesson 9

/

/bin /etc /mnt

/dir1

/dev/boot /home

/rsimms

/grub

/lost+found

/lost+found

/dir2

/lost+found

/lib

/dev/sda1

/dev/sda5

Mounting File SystemsLike pinning the tail on the donkey

/dev/sda6

mount /dev/sda6 /mnt

CIS 191 - Lesson 9

Mounting File SystemsCaveats

• Don’t mount a file system to a directory you are in.

• You can’t un-mount a file system you have cd’ed into:

[root@rh9 mnt]# umount /mntumount: /mnt: device is busy[root@rh9 mnt]# cd[root@rh9 root]# umount /mnt[root@rh9 root]#

CIS 191 - Lesson 9

CIS 191 - Lesson 9

[root@rh9 root]# mount/dev/sda2 on / type ext3 (rw)none on /proc type proc (rw)/dev/sda1 on /boot type ext2 (rw)none on /dev/pts type devpts (rw,gid=5,mode=620)/dev/sda5 on /home type ext3 (rw)none on /dev/shm type tmpfs (rw)

[root@rh9 root]# cat /etc/mtab/dev/sda2 / ext3 rw 0 0none /proc proc rw 0 0/dev/sda1 /boot ext2 rw 0 0none /dev/pts devpts rw,gid=5,mode=620 0 0/dev/sda5 /home ext3 rw 0 0none /dev/shm tmpfs rw 0 0[root@rh9 root]#

devicemount point

file system type

mount options

dump frequency

fsckpass

Note: spaces added to output above for readability

Mounting File Systemsmount command and /etc/mtab

CIS 191 - Lesson 9

[root@rh9 root]# cat /etc/fstab

LABEL=/ / ext3 defaults 1 1LABEL=/boot /boot ext2 defaults 1 2none /dev/pts devpts gid=5,mode=620 0 0LABEL=/home /home ext3 defaults 1 2none /proc proc defaults 0 0none /dev/shm tmpfs defaults 0 0/dev/sda3 swap swap defaults 0 0/dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro 0 0/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0

devicemount point

file system type

mount options

dump frequency

fsckpass

Note: spacing modified in output above for readability

Mounting File Systems/etc/fstab

/etc/fstab is used to automatically mount file systems at boot time

CIS 191 - Lesson 9

Usage

CIS 191 - Lesson 9

Disk space allocationdf and du commands

[root@benji bin]# du -sm /*7 /bin9 /boot1 /dev107 /etc1 /home112 /lib1 /lost+found1 /media0 /misc1 /mnt0 /net235 /opt0 /proc66 /root25 /sbin0 /selinux1 /srv0 /sys1 /tmp2370 /usr63 /var[root@benji bin]#

[root@benji mnt]# df -mFilesystem 1M-blocks Used Available Use% Mounted on/dev/sda1 2903 2399 355 88% /tmpfs 252 0 252 0% /dev/shm/dev/sda5 289 232 43 85% /opt/dev/sda3 487 72 390 16% /var/dev/sda7 196 6 181 3% /mnt

du (disk usage) shows how much space is being used and where -m (show in MB) -s (summarize)

df shows free space on a partition level -m (show in MB)

CIS 191 - Lesson 9

Quotas

CIS 191 - Lesson 9

Managing Quotas

• Set quotas by user or group• Soft and hard limits• Grace period allows temporarily exceeding soft limit• Hard limits cannot be exceeded• Can limit by space usage or number of files• Set on individual partitions

CIS 191 - Lesson 9

Managing Quotas

• RPM package[root@benji ~]# rpm -qa | grep quotaquota-3.13-1.2.3.2.el5[root@benji ~]#

• Installed by default with CentOS 5 (Benji VM)• Quota binary files kept in partition root directory• aquota.user• aquota.group

CIS 191 - Lesson 9

Managing Quotas Summary

CIS 191 - Lesson 9

Managing Quotas

CIS 191 - Lesson 9

Managing Quotas

-c option doesn't read existing data files -u checks only user quotas–v is for verbose reporting

CIS 191 - Lesson 9

Managing Quotas[root@benji ~]# ls -l /hometotal 32-rw------- 1 root root 9216 Nov 3 04:14 aquota.userdrwx------ 3 cis191 cis191 1024 Oct 25 15:31 cis191drwx------ 2 frodo hobbits 1024 Nov 2 18:07 frododrwx------ 2 gimli dwarves 1024 Nov 2 18:07 gimlidrwx------ 2 glorfindel elves 1024 Nov 2 18:07 legolasdrwx------ 2 root root 12288 Nov 3 02:58 lost+founddrwx------ 2 gollum hobbits 1024 Nov 2 18:07 smeagol[root@benji ~]# mount/dev/sda1 on / type ext3 (rw)proc on /proc type proc (rw)sysfs on /sys type sysfs (rw)devpts on /dev/pts type devpts (rw,gid=5,mode=620)tmpfs on /dev/shm type tmpfs (rw)/dev/sda5 on /opt type ext3 (rw)/dev/sda3 on /var type ext3 (rw)none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)/dev/sda7 on /home type ext3 (rw,usrquota)/root/bin/myfs on /mnt type ext2 (rw,loop=/dev/loop0)[root@benji ~]# file /home/aq*/home/aquota.user: data[root@benji ~]# User quota configuration is kept in a

binary file called aquota.user

created when you first run quotacheck command

CIS 191 - Lesson 9

Managing Quotas

CIS 191 - Lesson 9

Managing Quotas

Set soft limit to 2 MB and hard limit to 2.5MB

vi user interface!

CIS 191 - Lesson 9

Managing Quotas

Set soft limit to 4.5 MB and hard limit to 5MB for user gimli. No soft or hard limits on number of inodes

CIS 191 - Lesson 9

Managing Quotas

CIS 191 - Lesson 9

Managing Quotas

CIS 191 - Lesson 9

Managing Quotas

CIS 191 - Lesson 9

New commands:chattr - set extended file attributesfsck - Check and repair file systemdumpe2fs - Dump file system informatione2label - Change a file system labeldebugfs - Debug a file systemdu - Disk usage by directorydf - Disk usage by file systemedquota - specify quotaslsattr - list extended file attributesmkfs - make a file systemmount - mount a filesystemquotacheck - check quotasquotaoff - disable quotasquotaon - turn on quotasrepquota - report quotasstat - show inode informationtune2fs - Change or tune a file systemumount - un-mount a filesystem

New Files and Directories:/etc/fstab/etc/mtablost+foundaquota.user, aquota.group