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

Exercise:

4 adjust its reservation percentage to 3%

# tune2fs-m 3-L DATA / dev/sda7

5 to remount this file system without updating the access timestamp, and verify its effect

# stat / backup/inittab

# cat / backup/inittab

# stat

# mount-o remount,noatime / backup

# cat

# stat

6 force a test on this file system

E2fsch-f / dev/sda7

7 Delete all copied files and mount the file system back to sync:

Then copy all the word mount points in the / etc directory again to experience their performance changes

# rm-rf / backup/*

# mount-o remount,sync / backup

# cp-r / ect/* / backup

Cpu register is about 1ns first-level buffer (second-level cache) 10ns memory 10ms disk second level

(timesharing,multiplex)

CPU:time slice

Memory:

X86 (32bit): virtual address, linear address

Icano device:

Swap partitions: allow memory overload

Page out, page in

Free: view physical memory and interactive partition usage

-mm display

Adjust partition type Linux swap in fdisk / dev/sda fdisk

Partprobe / dev/sda

Create a swap partition:

Mkswap / dev/sda8

-L LABEL

Swapon / dev/sda8 enable swap partition

Swapoff / dev/sda8

Loopback device:

Loopback, using software to simulate the implementation of hardware

Create an image file, 120g

Dd command: dd if=/etc/inittab of=/root/inittab

If= data sources

Of= data storage target

How many units are replicated by bs=1 blocksize at a time

Count=2 has been copied several times.

The amount of space skipped when seek=#: creates a data file

Dd if=/dev/sda of=/mnt/usb/mbr.backup bs=512 count=1 backup

Dd if=/mnt/usb/mbr.backup of=/dev/sda bs=512 count=1 recovery

Cat / dev/cdrom > / root/rhel5.iso make CD image

Dd if=/dev/zero of=/var/swapfile bs=1M count=1024

Mkswap / var/swapfile

Swapon / var/swapfile

Dd if=/dev/zero of=/var/swapfile seek=1023 bs=1M count=1

Seek= skips 1023, but it is only 1m, which is virtualized as 1G (du-sh / var/sawpfile2 view)

Real space, ls can't see real space)

Mount command, you can mount the iso image

Mount DEVICE MOUNT_POINT

-o loop: mounts the local loopback device

Wget ftp://172.16.0.1/pub/isos/rhci-5.8-1.iso

Mount-o loop / root/rhci-5.8-1.iso / media/

Swapon-an enables all switching devices defined in the / etc/fstab file

Configuration file / etc/fstab for the file system

The disk written in this file will be mounted automatically, but will not be mounted automatically after the mount command is restarted.

When OS initializes, it automatically mounts each file system defined in this file

/ content of etc/fstab

Device mount point to mount file system type mount option dump frequency (how many days to do a full backup) file system detection order (only root can be 1, no check)

Dump frequency: how often does it take to make a full backup of this file system

0 do not back up

one

2 every 2 days

Mount-a: Mount all file systems defined in the / etc/fstab file

Fuser-v / mnt/test to see which users are accessing mounted devices

Fuser: verify the file or socket file being used by the process

-v View that a file is running

-k

-m

Fuser-km MOUNT_POINT terminates all processes that are accessing this mount point

Virtual memory:

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