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246 lines
8.7 KiB
ReStructuredText
246 lines
8.7 KiB
ReStructuredText
.. _raid:
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######
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RAID-1
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######
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A Redundant Array of Independent Disks (RAID) uses two or more hard disk drives
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to improve disk speed, store more data, and/or provide fault tolerance.
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There are several storage schemes possible in a RAID array, each offering a
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different combination of storage, reliability, and/or performance.
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The VyOS system supports a “RAID 1” deployment. RAID 1 allows two or more
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disks to mirror one another to provide system fault tolerance. In a RAID 1
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solution, every sector of one disk is duplicated onto every sector of all
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disks in the array. Provided even one disk in the RAID 1 set is operational,
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the system continues to run, even through disk replacement (provided that the
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hardware supports in-service replacement of drives).
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RAID 1 can be implemented using special hardware or it can be implemented in
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software. The VyOS system supports software RAID 1 on two disks.
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The VyOS implementation of RAID 1 allows the following:
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* Detection and reporting of disk failure
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* The ability to maintain system operation with one failed disk
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* The ability to boot the system with one failed disk
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* The ability to replace a failed disk and initiate re-mirroring
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* The ability to monitor the status of remirroring
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.. _raid_instalation:
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Installation Implications
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=========================
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The VyOS systems installation utility provides several options for installing
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to a RAID 1 set. You can:
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* Use the install system to create the RAID 1 set
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* Use the underlying Linux commands to create a RAID 1 set before running the
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install system command.
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* Use a previously-created RAID 1 set.
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.. note:: Before a permanent installation, VyOS runs a live installation
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Configuration
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=============
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Single disk, install as normal
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------------------------------
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When the VyOS system is installed, it automatically detects the presence of two
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disks not currently part of a RAID array. In these cases, the VyOS
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installation utility automatically offers you the option of configuring RAID 1
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mirroring for the drives, with the following prompt.
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.. code-block:: none
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Would you like to configure RAID 1 mirroring on them?
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* If you do not want to configure RAID 1 mirroring, enter “No” at the prompt
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and continue with installation in the normal way.
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Empty 2+ Disk
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-------------
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If VyOS system detect two identical disks that are not currently part of a
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RAID-1 set, the VyOS installation utility automatically offers you the option
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of configuring RAID 1 mirroring for the drives, with the following prompt.
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.. code-block:: none
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Would you like to configure RAID 1 mirroring on them?
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1 - To create a new RAID 1 array, enter “Yes” at the prompt. If the system
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detects a filesystem on the partitions being used for RAID 1 it will prompt you
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to indicate whether you want to continue creating the RAID 1 array.
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.. code-block:: none
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Continue creating array?
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2 - To overwrite the old filesystem, enter “Yes”.
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3 - The system informs you that all data on both drives will be erased. You are
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prompted to confirm that you want to continue
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.. code-block:: none
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Are you sure you want to do this?
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4 - Enter “Yes” at the prompt to retain the current VyOS configuration once
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installation is complete. Enter “No” to delete the current VyOS
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configuration.
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.. code-block:: none
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Would you like me to save the data on it before I delete it?
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5 - Enter “Yes” at the prompt to retain the current VyOS configuration once
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installation is complete. Enter “No” to delete the current VyOS configuration.
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6 - Continue with installation in the normal way.
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Present RAID-1
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--------------
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When the VyOS software on a system with a RAID 1 set already configured,
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the installation utility will detect the array and will display the following
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prompt:
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.. code-block:: none
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Would you like to use this one?
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1 - To break apart the current RAID 1 set, enter “No” at the prompt. The
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installation utility detects that there are two identical disks and offers you
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the option of configuring RAID 1 mirroring on them, displaying the following
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prompt:
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.. code-block:: none
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Would you like to configure RAID 1 mirroring on them?
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2 - To decline to set up a new RAID 1 configuration on the disks, enter “No”
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at the prompt. The system prompts you to indicate which partition you would
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like the system installed on.
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.. code-block:: none
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Which partition should I install the root on? [sda1]:
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3 - Enter the partition where you would like the system installed. The system
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then prompts you to indicate whether you want to save the old configuration
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data. This represents the current VyOS configuration.
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.. code-block:: none
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Would you like me to save the data on it before I delete it?
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4 - Enter “Yes” at the prompt to retain the current VyOS configuration once
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installation is complete. Enter “No” to delete the current VyOS configuration.
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5 - Continue with installation in the normal way.
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Detecting and Replacing a Failed RAID 1 Disk
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--------------------------------------------
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The VyOS system automatically detects a disk failure within a RAID 1 set and
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reports it to the system console. You can verify the failure by issuing the
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show raid command.
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To replace a bad disk within a RAID 1 set, perform the following steps:
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1 - Remove the failed disk from the RAID 1 set by issuing the following
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command:
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.. opcmd:: delete raid <RAID‐1‐device> member <disk‐partition>
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where RAID-1-device is the name of the RAID 1 device (for example, md0) and
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disk-partition is the name of the failed disk partition (for example, sdb2).
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2- Physically remove the failed disk from the system. If the drives are not
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hot-swappable, then you must shut down the system before removing the disk.
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3 - Replace the failed drive with a drive of the same size or larger.
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4 - Format the new disk for RAID 1 by issuing the following command:
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.. opcmd:: format disk <disk‐device1> like <disk‐device2>
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where disk-device1 is the replacement disk (for example, sdb) and
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disk-device2 is the existing healthy disk (for example, sda).
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5-Add the replacement disk to the RAID 1 set by issuing the following command:
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.. opcmd:: add raid <RAID‐1‐device> member <disk‐partition>
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where RAID-1-device is the name of the RAID 1 device (for example, md0) and
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disk-partition is the name of the replacement disk partition
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(for example, sdb2).
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Operation
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=========
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This part introduces how to add a disk partition to a RAID-1 set initiates
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mirror synchronization, check and display information.
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.. opcmd:: add raid <RAID‐1‐device> member <disk‐partition>
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Use this command to add a member disk partition to the RAID 1 set. Adding a
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disk partition to a RAID 1 set initiates mirror synchronization, where all
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data on the existing member partition is copied to the new partition.
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.. opcmd:: format disk <disk‐device1> like <disk‐device2>
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This command is typically used to prepare a disk to be added to a preexisting
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RAID 1 set (of which disk-device2 is already a member).
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.. opcmd:: show raid <RAID‐1‐device>
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shows output for show raid md0 as sdb1 is being added to the RAID 1
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set and is in the process of being resynchronized.
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.. code-block:: none
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vyos@vyos:~$ show raid md0
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/dev/md0:
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Version : 00.90
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Creation Time : Wed Oct 29 09:19:09 2008
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Raid Level : raid1
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Array Size : 1044800 (1020.48 MiB 1069.88 MB)
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Used Dev Size : 1044800 (1020.48 MiB 1069.88 MB)
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Raid Devices : 2
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Total Devices : 2
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Preferred Minor : 0
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Persistence : Superblock is persistent
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Update Time : Wed Oct 29 19:34:23 2008
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State : active, degraded, recovering
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Active Devices : 1
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Working Devices : 2
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Failed Devices : 0
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Spare Devices : 1
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Rebuild Status : 17% complete
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UUID : 981abd77:9f8c8dd8:fdbf4de4:3436c70f
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Events : 0.103
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Number Major Minor RaidDevice State
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0 8 1 0 active sync /dev/sda1
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2 8 17 1 spare rebuilding /dev/sdb1
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.. opcmd:: show raid <RAID‐1‐device>
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Use this command to display the formatting of a hard disk.
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.. code-block:: none
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vyos@vyos:~$ show disk sda format
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Disk /dev/sda: 1073 MB, 1073741824 bytes
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85 heads, 9 sectors/track, 2741 cylinders
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Units = cylinders of 765 * 512 = 391680 bytes
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Disk identifier: 0x000b7179
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Device Boot Start End Blocks Id System
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/dev/sda1 6 2737 1044922+ fd Linux raid autodetect
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