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[Translating by cposture 15-12-31]
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Part 6 - LFCS: Assembling Partitions as RAID Devices – Creating & Managing System Backups
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================================================================================
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Recently, the Linux Foundation launched the LFCS (Linux Foundation Certified Sysadmin) certification, a shiny chance for system administrators everywhere to demonstrate, through a performance-based exam, that they are capable of performing overall operational support on Linux systems: system support, first-level diagnosing and monitoring, plus issue escalation, when required, to other support teams.
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Linux Foundation Certified Sysadmin – Part 6
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The following video provides an introduction to The Linux Foundation Certification Program.
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注：youtube 视频
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<iframe width="720" height="405" frameborder="0" allowfullscreen="allowfullscreen" src="//www.youtube.com/embed/Y29qZ71Kicg"></iframe>
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This post is Part 6 of a 10-tutorial series, here in this part, we will explain How to Assemble Partitions as RAID Devices – Creating & Managing System Backups, that are required for the LFCS certification exam.
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### Understanding RAID ###
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The technology known as Redundant Array of Independent Disks (RAID) is a storage solution that combines multiple hard disks into a single logical unit to provide redundancy of data and/or improve performance in read / write operations to disk.
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However, the actual fault-tolerance and disk I/O performance lean on how the hard disks are set up to form the disk array. Depending on the available devices and the fault tolerance / performance needs, different RAID levels are defined. You can refer to the RAID series here in Tecmint.com for a more detailed explanation on each RAID level.
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- RAID Guide: [What is RAID, Concepts of RAID and RAID Levels Explained][1]
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Our tool of choice for creating, assembling, managing, and monitoring our software RAIDs is called mdadm (short for multiple disks admin).
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---------------- Debian and Derivatives ----------------
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# aptitude update && aptitude install mdadm
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----------
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---------------- Red Hat and CentOS based Systems ----------------
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# yum update && yum install mdadm
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----------
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---------------- On openSUSE ----------------
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# zypper refresh && zypper install mdadm #
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#### Assembling Partitions as RAID Devices ####
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The process of assembling existing partitions as RAID devices consists of the following steps.
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**1. Create the array using mdadm**
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If one of the partitions has been formatted previously, or has been a part of another RAID array previously, you will be prompted to confirm the creation of the new array. Assuming you have taken the necessary precautions to avoid losing important data that may have resided in them, you can safely type y and press Enter.
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# mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sdb1 /dev/sdc1
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Creating RAID Array
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**2. Check the array creation status**
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After creating RAID array, you an check the status of the array using the following commands.
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# cat /proc/mdstat
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or
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# mdadm --detail /dev/md0 [More detailed summary]
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Check RAID Array Status
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**3. Format the RAID Device**
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Format the device with a filesystem as per your needs / requirements, as explained in [Part 4][2] of this series.
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**4. Monitor RAID Array Service**
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Instruct the monitoring service to “keep an eye” on the array. Add the output of mdadm –detail –scan to /etc/mdadm/mdadm.conf (Debian and derivatives) or /etc/mdadm.conf (CentOS / openSUSE), like so.
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# mdadm --detail --scan
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Monitor RAID Array
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# mdadm --assemble --scan [Assemble the array]
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To ensure the service starts on system boot, run the following commands as root.
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**Debian and Derivatives**
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Debian and derivatives, though it should start running on boot by default.
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# update-rc.d mdadm defaults
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Edit the /etc/default/mdadm file and add the following line.
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AUTOSTART=true
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**On CentOS and openSUSE (systemd-based)**
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# systemctl start mdmonitor
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# systemctl enable mdmonitor
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**On CentOS and openSUSE (SysVinit-based)**
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# service mdmonitor start
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# chkconfig mdmonitor on
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**5. Check RAID Disk Failure**
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In RAID levels that support redundancy, replace failed drives when needed. When a device in the disk array becomes faulty, a rebuild automatically starts only if there was a spare device added when we first created the array.
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Check RAID Faulty Disk
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Otherwise, we need to manually attach an extra physical drive to our system and run.
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# mdadm /dev/md0 --add /dev/sdX1
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Where /dev/md0 is the array that experienced the issue and /dev/sdX1 is the new device.
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**6. Disassemble a working array**
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You may have to do this if you need to create a new array using the devices – (Optional Step).
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# mdadm --stop /dev/md0 # Stop the array
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# mdadm --remove /dev/md0 # Remove the RAID device
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# mdadm --zero-superblock /dev/sdX1 # Overwrite the existing md superblock with zeroes
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**7. Set up mail alerts**
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You can configure a valid email address or system account to send alerts to (make sure you have this line in mdadm.conf). – (Optional Step)
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MAILADDR root
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In this case, all alerts that the RAID monitoring daemon collects will be sent to the local root account’s mail box. One of such alerts looks like the following.
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**Note**: This event is related to the example in STEP 5, where a device was marked as faulty and the spare device was automatically built into the array by mdadm. Thus, we “ran out” of healthy spare devices and we got the alert.
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RAID Monitoring Alerts
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#### Understanding RAID Levels ####
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**RAID 0**
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The total array size is n times the size of the smallest partition, where n is the number of independent disks in the array (you will need at least two drives). Run the following command to assemble a RAID 0 array using partitions /dev/sdb1 and /dev/sdc1.
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# mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sdb1 /dev/sdc1
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Common uses: Setups that support real-time applications where performance is more important than fault-tolerance.
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**RAID 1 (aka Mirroring)**
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The total array size equals the size of the smallest partition (you will need at least two drives). Run the following command to assemble a RAID 1 array using partitions /dev/sdb1 and /dev/sdc1.
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# mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
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Common uses: Installation of the operating system or important subdirectories, such as /home.
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**RAID 5 (aka drives with Parity)**
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The total array size will be (n – 1) times the size of the smallest partition. The “lost” space in (n-1) is used for parity (redundancy) calculation (you will need at least three drives).
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Note that you can specify a spare device (/dev/sde1 in this case) to replace a faulty part when an issue occurs. Run the following command to assemble a RAID 5 array using partitions /dev/sdb1, /dev/sdc1, /dev/sdd1, and /dev/sde1 as spare.
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# mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --spare-devices=1 /dev/sde1
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Common uses: Web and file servers.
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**RAID 6 (aka drives with double Parity**
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The total array size will be (n*s)-2*s, where n is the number of independent disks in the array and s is the size of the smallest disk. Note that you can specify a spare device (/dev/sdf1 in this case) to replace a faulty part when an issue occurs.
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Run the following command to assemble a RAID 6 array using partitions /dev/sdb1, /dev/sdc1, /dev/sdd1, /dev/sde1, and /dev/sdf1 as spare.
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# mdadm --create --verbose /dev/md0 --level=6 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde --spare-devices=1 /dev/sdf1
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Common uses: File and backup servers with large capacity and high availability requirements.
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**RAID 1+0 (aka stripe of mirrors)**
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The total array size is computed based on the formulas for RAID 0 and RAID 1, since RAID 1+0 is a combination of both. First, calculate the size of each mirror and then the size of the stripe.
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Note that you can specify a spare device (/dev/sdf1 in this case) to replace a faulty part when an issue occurs. Run the following command to assemble a RAID 1+0 array using partitions /dev/sdb1, /dev/sdc1, /dev/sdd1, /dev/sde1, and /dev/sdf1 as spare.
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# mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sd[b-e]1 --spare-devices=1 /dev/sdf1
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Common uses: Database and application servers that require fast I/O operations.
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#### Creating and Managing System Backups ####
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It never hurts to remember that RAID with all its bounties IS NOT A REPLACEMENT FOR BACKUPS! Write it 1000 times on the chalkboard if you need to, but make sure you keep that idea in mind at all times. Before we begin, we must note that there is no one-size-fits-all solution for system backups, but here are some things that you do need to take into account while planning a backup strategy.
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- What do you use your system for? (Desktop or server? If the latter case applies, what are the most critical services – whose configuration would be a real pain to lose?)
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- How often do you need to take backups of your system?
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- What is the data (e.g. files / directories / database dumps) that you want to backup? You may also want to consider if you really need to backup huge files (such as audio or video files).
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- Where (meaning physical place and media) will those backups be stored?
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**Backing Up Your Data**
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Method 1: Backup entire drives with dd command. You can either back up an entire hard disk or a partition by creating an exact image at any point in time. Note that this works best when the device is offline, meaning it’s not mounted and there are no processes accessing it for I/O operations.
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The downside of this backup approach is that the image will have the same size as the disk or partition, even when the actual data occupies a small percentage of it. For example, if you want to image a partition of 20 GB that is only 10% full, the image file will still be 20 GB in size. In other words, it’s not only the actual data that gets backed up, but the entire partition itself. You may consider using this method if you need exact backups of your devices.
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**Creating an image file out of an existing device**
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# dd if=/dev/sda of=/system_images/sda.img
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OR
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--------------------- Alternatively, you can compress the image file ---------------------
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# dd if=/dev/sda | gzip -c > /system_images/sda.img.gz
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**Restoring the backup from the image file**
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# dd if=/system_images/sda.img of=/dev/sda
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OR
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--------------------- Depending on your choice while creating the image ---------------------
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gzip -dc /system_images/sda.img.gz | dd of=/dev/sda
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Method 2: Backup certain files / directories with tar command – already covered in [Part 3][3] of this series. You may consider using this method if you need to keep copies of specific files and directories (configuration files, users’ home directories, and so on).
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Method 3: Synchronize files with rsync command. Rsync is a versatile remote (and local) file-copying tool. If you need to backup and synchronize your files to/from network drives, rsync is a go.
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Whether you’re synchronizing two local directories or local < — > remote directories mounted on the local filesystem, the basic syntax is the same.
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Synchronizing two local directories or local < — > remote directories mounted on the local filesystem
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# rsync -av source_directory destination directory
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Where, -a recurse into subdirectories (if they exist), preserve symbolic links, timestamps, permissions, and original owner / group and -v verbose.
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rsync Synchronizing Files
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In addition, if you want to increase the security of the data transfer over the wire, you can use ssh over rsync.
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**Synchronizing local → remote directories over ssh**
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# rsync -avzhe ssh backups root@remote_host:/remote_directory/
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This example will synchronize the backups directory on the local host with the contents of /root/remote_directory on the remote host.
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Where the -h option shows file sizes in human-readable format, and the -e flag is used to indicate a ssh connection.
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rsync Synchronize Remote Files
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Synchronizing remote → local directories over ssh.
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In this case, switch the source and destination directories from the previous example.
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# rsync -avzhe ssh root@remote_host:/remote_directory/ backups
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Please note that these are only 3 examples (most frequent cases you’re likely to run into) of the use of rsync. For more examples and usages of rsync commands can be found at the following article.
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- Read Also: [10 rsync Commands to Sync Files in Linux][4]
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### Summary ###
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As a sysadmin, you need to ensure that your systems perform as good as possible. If you’re well prepared, and if the integrity of your data is well supported by a storage technology such as RAID and regular system backups, you’ll be safe.
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If you have questions, comments, or further ideas on how this article can be improved, feel free to speak out below. In addition, please consider sharing this series through your social network profiles.
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--------------------------------------------------------------------------------
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via: http://www.tecmint.com/creating-and-managing-raid-backups-in-linux/
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作者：[Gabriel Cánepa][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://www.tecmint.com/author/gacanepa/
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[1]:http://www.tecmint.com/understanding-raid-setup-in-linux/
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[2]:http://www.tecmint.com/create-partitions-and-filesystems-in-linux/
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[3]:http://www.tecmint.com/compress-files-and-finding-files-in-linux/
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[4]:http://www.tecmint.com/rsync-local-remote-file-synchronization-commands/
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@ -1,24 +1,26 @@
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[未完成，不要合并-Translating By cposture 2016-01-07]
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LFCS 系列第六讲：//创建和管理系统备份
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====
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LFCS 系列第六讲：组装分区为RAID设备——创建和管理系统备份
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=========================================================
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Linux 基金会已经发起了一个全新的 LFCS（Linux Foundation Certified Sysadmin，Linux 基金会认证系统管理员）认证，旨在让来自世界各地的人有机会参加到 LFCS 测试，获得关于有能力在 Linux 系统中执行中间系统管理任务的认证。该认证包括：维护正在运行的系统和服务的能力、全面监控和分析的能力以及何时上游团队请求支持的决策能力。
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//图片
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LFCS 系列第五讲
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LFCS 系列第六讲
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以下视频介绍了 Linux 基金会认证程序。
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本讲是《十套教程》系列中的第六讲，在这一讲里，我们将会解释如何组装分区作为RAID设备——创建和管理系统备份。这些都是 LFCS 认证中的必备知识。
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注：youtube 视频
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<iframe width="720" height="405" frameborder="0" allowfullscreen="allowfullscreen" src="//www.youtube.com/embed/Y29qZ71Kicg"></iframe>
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# 了解RAID
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本讲是《十套教程》系列中的第六讲，在这一讲里，我们将会解释如何组装分区为RAID设备——创建和管理系统备份。这些都是 LFCS 认证中的必备知识。
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被称为独立磁盘冗余阵列(RAID)的技术是一种将多个硬盘组合成一个单独逻辑单元的存储解决方案，它提供了数据冗余功能并且改善硬盘的读写性能。
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### 了解RAID ###
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一种被称为独立磁盘冗余阵列(RAID)的技术是将多个硬盘组合成一个单独逻辑单元的存储解决方案，它提供了数据冗余功能并且改善硬盘的读写操作性能。
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然而，实际的容错和磁盘I/O性能硬盘取决于如何将多个硬盘组装成磁盘阵列。根据可用的设备和容错/性能的需求，RAID被分为不同的级别，你可以在Tecmint.com上参考RAID系列文章以获得每个RAID级别更详细的解释。
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* //网址
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- RAID Guide: [What is RAID, Concepts of RAID and RAID Levels Explained][1]
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我们选择用于创建、组装、管理、监视软件RAID的工具，叫做mdadm(multiple disk admin的简写)。
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@ -37,11 +39,11 @@ LFCS 系列第五讲
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# zypper refresh && zypper install mdadm #
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```
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## 组装分区作为RAID设备
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#### 组装分区作为RAID设备 ####
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组装已有分区作为RAID设备的过程由以下步骤组成。
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1. 使用mdadm创建阵列
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**1. 使用mdadm创建阵列**
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如果先前其中一个分区被格式化，或者作为了另一个RAID阵列的一部分，你会被提示以确认创建一个新的阵列。假设你已经采取了必要的预防措施以避免丢失重要数据，那么可以安全地输入Y并且按下回车。
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@ -49,107 +51,235 @@ LFCS 系列第五讲
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# mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sdb1 /dev/sdc1
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```
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//图片
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创建RAID阵列
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2. 检查阵列的创建状态
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**2. 检查阵列的创建状态**
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在创建了RAID阵列之后，你可以检查使用以下命令检查阵列的状态
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在创建了RAID阵列之后，你可以检查使用以下命令检查阵列的状态。
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```
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# cat /proc/mdstat
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or
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# mdadm --detail /dev/md0 [More detailed summary]
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```
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//图片
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# cat /proc/mdstat
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or
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# mdadm --detail /dev/md0 [More detailed summary]
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检查RAID阵列的状态
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3. 格式化RAID设备
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**3. 格式化RAID设备**
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如本系列4部分所介绍的，按照你的需求/要求采用某种文件系统格式化你的设备
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如本系列[Part 4][2]所介绍的，按照你的需求/要求采用某种文件系统格式化你的设备。
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4. 监控RAID阵列服务
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指示监控服务时刻监视你的RAID阵列。把```# mdadm --detail --scan```命令输出结果添加到/etc/mdadm/mdadm.conf(Debian和derivatives)或者/etc/mdadm.conf(Cent0S/openSUSE)，如下。
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```
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# mdadm --detail --scan
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```
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//图片
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# mdadm --detail --scan
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||||
|
||||
|
||||
|
||||
|
||||
监控RAID阵列
|
||||
|
||||
```
|
||||
# mdadm --assemble --scan [Assemble the array]
|
||||
```
|
||||
# mdadm --assemble --scan [Assemble the array]
|
||||
|
||||
为了确保服务能够开机启动，需要以root权限运行以下命令。
|
||||
|
||||
## Debian 和 Derivatives
|
||||
**Debian 和 Derivatives**
|
||||
|
||||
Debian 和 Derivatives能够通过下面步骤使服务默认开机启动
|
||||
```
|
||||
# update-rc.d mdadm defaults
|
||||
```
|
||||
|
||||
# update-rc.d mdadm defaults
|
||||
|
||||
在/etc/default/mdadm文件中添加下面这一行
|
||||
```
|
||||
AUTOSTART=true
|
||||
```
|
||||
|
||||
## CentOS 和 openSUSE(systemd-based)
|
||||
AUTOSTART=true
|
||||
|
||||
```
|
||||
# systemctl start mdmonitor
|
||||
# systemctl enable mdmonitor
|
||||
```
|
||||
|
||||
## CentOS 和 openSUSEi(SysVinit-based)
|
||||
**CentOS 和 openSUSE(systemd-based)**
|
||||
|
||||
```
|
||||
# service mdmonitor start
|
||||
# chkconfig mdmonitor on
|
||||
```
|
||||
# systemctl start mdmonitor
|
||||
# systemctl enable mdmonitor
|
||||
|
||||
5. 检查RAID磁盘故障
|
||||
**CentOS 和 openSUSEi(SysVinit-based)**
|
||||
|
||||
# service mdmonitor start
|
||||
# chkconfig mdmonitor on
|
||||
|
||||
**5. 检查RAID磁盘故障**
|
||||
|
||||
在支持冗余的的RAID级别中，在需要时会替换故障的驱动器。当磁盘阵列中的设备出现故障时，仅当存在我们第一次创建阵列时预留的备用设备时，磁盘阵列会将自动启动重建。
|
||||
|
||||
//图片
|
||||
|
||||
|
||||
检查RAID故障磁盘
|
||||
|
||||
否则，我们需要手动连接一个额外的物理驱动器到我们的系统，并且运行。
|
||||
|
||||
```
|
||||
# mdadm /dev/md0 --add /dev/sdX1
|
||||
```
|
||||
# mdadm /dev/md0 --add /dev/sdX1
|
||||
|
||||
/dev/md0是出现了问题的阵列，而/dev/sdx1是新添加的设备。
|
||||
|
||||
6. 分解一个工作阵列
|
||||
**6. 分解一个工作阵列**
|
||||
|
||||
如果你需要使用工作阵列的设备创建一个新的阵列，你可能不得不去分解已有工作阵列——(可选步骤)
|
||||
|
||||
```
|
||||
# mdadm --stop /dev/md0 # Stop the array
|
||||
# mdadm --remove /dev/md0 # Remove the RAID device
|
||||
# mdadm --zero-superblock /dev/sdX1 # Overwrite the existing md superblock with zeroes
|
||||
```
|
||||
# mdadm --stop /dev/md0 # Stop the array
|
||||
# mdadm --remove /dev/md0 # Remove the RAID device
|
||||
# mdadm --zero-superblock /dev/sdX1 # Overwrite the existing md superblock with zeroes
|
||||
|
||||
7. 设置邮件通知
|
||||
**7. 设置邮件通知**
|
||||
|
||||
你可以配置一个用于发送通知的有效邮件地址或者系统账号(确保在mdadm.conf文件中有下面这一行)。——(可选步骤)
|
||||
```
|
||||
MAILADDR root
|
||||
```
|
||||
|
||||
MAILADDR root
|
||||
|
||||
在这种情况下，来自RAID后台监控程序所有的通知将会发送到你的本地root账号的邮件箱中。其中一个类似的通知如下。
|
||||
|
||||
说明：此次通知事件和第5步中的例子相关。一个设备被标志为错误并且一个空闲的设备自动地被mdadm加入到阵列。我们用完了所有"健康的"空闲设备，因此我们得到了通知。
|
||||
|
||||
//图片
|
||||
|
||||
|
||||
RAID监控通知
|
||||
|
||||
#### 了解RAID级别 ####
|
||||
|
||||
** RAID 0 **
|
||||
|
||||
阵列总大小是最小分区大小的n倍，n是阵列中独立磁盘的个数(你至少需要两个驱动器/磁盘)。运行下面命令，使用/dev/sdb1和/dev/sdc1分区组装一个RAID 0 阵列。
|
||||
|
||||
# mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sdb1 /dev/sdc1
|
||||
|
||||
常见用途：用于支持性能比容错更重要的实时应用程序的设置
|
||||
|
||||
**RAID 1 (又名镜像/Mirroring)**
|
||||
|
||||
阵列总大小等于最小分区大小(你至少需要两个驱动器/磁盘)。运行下面命令，使用/dev/sdb1和/dev/sdc1分区组装一个RAID 1 阵列。
|
||||
|
||||
# mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
|
||||
|
||||
常见用途：操作系统的安装或者重要的子文件夹，例如 /home
|
||||
|
||||
**RAID 5 (又名奇偶校验码盘/drives with Parity)**
|
||||
|
||||
阵列总大小将是最小分区大小的(n-1)倍。//用于奇偶校验(冗余)计算(你至少需要3个驱动器/磁盘)。
|
||||
|
||||
说明：你可以指定一个空闲设备(/dev/sde1)替换问题出现时的故障部分(分区)。运行下面命令，使用/dev/sdb1, /dev/sdc1, /dev/sdd1，/dev/sde1组装一个RAID 5 阵列，其中/dev/sde1作为空闲分区。
|
||||
|
||||
# mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --spare-devices=1 /dev/sde1
|
||||
|
||||
常见用途：Web和文件服务
|
||||
|
||||
**RAID 6 (又名双重奇偶校验码盘/drives with double Parity)**
|
||||
|
||||
阵列总大小为(n*s)-2*s，其中n为阵列中独立磁盘的个数，s为最小磁盘大小。
|
||||
|
||||
说明：你可以指定一个空闲分区(在这个例子为/dev/sdf1)替换问题出现时的故障部分(分区)。
|
||||
|
||||
运行下面命令，使用/dev/sdb1, /dev/sdc1, /dev/sdd1, /dev/sde1和/dev/sdf1组装RAID 6阵列，其中/dev/sdf1作为空闲分区。
|
||||
|
||||
# mdadm --create --verbose /dev/md0 --level=6 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde --spare-devices=1 /dev/sdf1
|
||||
|
||||
常见用途：大容量、高可用性要求的文件服务器和备份服务器。
|
||||
|
||||
**RAID 1+0 (又名镜像条带/stripe of mirrors)**
|
||||
|
||||
因为RAID 1+0是RAID 0 和 RAID 1的组合，所以阵列总大小是基于两者的公式计算的。首先，计算每一个镜像的大小，然后再计算条带的大小。
|
||||
|
||||
|
||||
# mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sd[b-e]1 --spare-devices=1 /dev/sdf1
|
||||
|
||||
常见用途：需要快速IO操作的数据库和应用服务器
|
||||
|
||||
#### 创建和管理系统备份 ####
|
||||
|
||||
记住RAID其所有的价值不是在于备份的替换者是对你有益的！在黑板上写上1000次，如果你需要的话，但无论何时一定要记住它。在我们开始前，我们必须注意的是，没有一个放之四海皆准的针对所有系统备份的解决方案，但这里有一些东西，是你在规划一个备份策略时需要考虑的。
|
||||
|
||||
- 你的系统将用于什么？(桌面或者服务器？如果系统是应用于后者，那么最重要的服务是什么——//其配置？)
|
||||
- 你每隔多久备份你的系统？
|
||||
- 你需要备份的数据是什么(比如 文件/文件夹/数据库转储)？你还可以考虑是否需要备份大型文件(比如音频和视频文件)。
|
||||
- 这些备份将会存储在哪里(物理位置和媒体)？
|
||||
|
||||
**备份你的数据**
|
||||
|
||||
方法1：使用dd命令备份整个磁盘。你可以在任意时间点通过创建一个准确的镜像来备份一整个硬盘或者是分区。注意当设备是离线时，这种方法效果最好，也就是说它没有被挂载并且没有任何进程的I/O操作访问它。
|
||||
|
||||
这种备份方法的缺点是镜像将具有和磁盘或分区一样的大小，即使实际数据占用的是一个很小的比例。比如，如果你想要为只使用了10%的20GB的分区创建镜像，那么镜像文件将仍旧是20GB。换句话来讲，它不仅包含了备份的实际数据，而且也包含了整个分区。如果你想完整备份你的设备，那么你可以考虑使用这个方法。
|
||||
|
||||
**从现有的设备创建一个镜像文件**
|
||||
|
||||
# dd if=/dev/sda of=/system_images/sda.img
|
||||
或者
|
||||
--------------------- 可选地，你可以压缩镜像文件 -------------------
|
||||
# dd if=/dev/sda | gzip -c > /system_images/sda.img.gz
|
||||
|
||||
**从镜像文件恢复备份**
|
||||
|
||||
# dd if=/system_images/sda.img of=/dev/sda
|
||||
或者
|
||||
--------------------- 根据你创建镜像文件时的选择(译者注:比如压缩) ----------------
|
||||
# gzip -dc /system_images/sda.img.gz | dd of=/dev/sda
|
||||
|
||||
方法2：使用tar命令备份确定的文件/文件夹——已经在本系列[Part 3][3]中讲了。如果你想要备份指定的文件/文件夹(配置文件，用户主目录等等)，你可以使用这种方法。
|
||||
|
||||
方法3：使用rsync命令同步文件。rsync是一种多功能远程（和本地）文件复制工具。如果你想要从网络设备备份或同步文件，rsync是一种选择。
|
||||
|
||||
|
||||
无论是你是正在同步两个本地文件夹还是本地 < — > 挂载在本地文件系统的远程文件夹，其基本语法是一样的。
|
||||
|
||||
# rsync -av source_directory destination directory
|
||||
|
||||
在这里，-a 递归遍历子目录(如果它们存在的话)，维持符号链接、时间戳、权限以及原本的属主/属组，-v 显示详细过程。
|
||||
|
||||
|
||||
|
||||
rsync 同步文件
|
||||
|
||||
除此之外，如果你想增加在网络上传输数据的安全性，你可以通过rsync使用ssh协议。
|
||||
|
||||
**通过ssh同步本地 → 远程文件夹**
|
||||
|
||||
# rsync -avzhe ssh backups root@remote_host:/remote_directory/
|
||||
|
||||
这个示例，本地主机上的backups文件夹将与远程主机上的/root/remote_directory的内容同步。
|
||||
|
||||
在这里，-h 选项以人可读的格式显示文件的大小，-e 标志用于表示一个ssh连接。
|
||||
|
||||
|
||||
|
||||
rsync 同步远程文件
|
||||
|
||||
**通过ssh同步远程 → 本地 文件夹**
|
||||
|
||||
在这种情况下，交换前面示例中的source和destination文件夹。
|
||||
|
||||
# rsync -avzhe ssh root@remote_host:/remote_directory/ backups
|
||||
|
||||
请注意这些只是rsync用法的三个示例而已(你可能遇到的最常见的情形)。对于更多有关rsync命令的示例和用法 ，你可以查看下面的文章。
|
||||
|
||||
- Read Also: [10 rsync Commands to Sync Files in Linux][4]
|
||||
|
||||
### Summary ###
|
||||
|
||||
作为一个系统管理员，你需要确保你的系统表现得尽可能好。如果你做好了充分准备，并且如果你的数据完整性能被诸如RAID和系统日常备份的存储技术支持，那你将是安全的。
|
||||
|
||||
如果你有有关完善这篇文章的问题、评论或者进一步的想法，可以在下面畅所欲言。除此之外，请考虑通过你的社交网络简介分享这系列文章。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.tecmint.com/creating-and-managing-raid-backups-in-linux/
|
||||
|
||||
作者：[Gabriel Cánepa][a]
|
||||
译者：[cpsoture](https://github.com/cposture)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.tecmint.com/author/gacanepa/
|
||||
[1]:http://www.tecmint.com/understanding-raid-setup-in-linux/
|
||||
[2]:http://www.tecmint.com/create-partitions-and-filesystems-in-linux/
|
||||
[3]:http://www.tecmint.com/compress-files-and-finding-files-in-linux/
|
||||
[4]:http://www.tecmint.com/rsync-local-remote-file-synchronization-commands/
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user