RAID 1

A Redundant Array of Independent Disks (RAID) uses two or more hard disk drives to improve disk speed, store more data, and/or provide fault tolerance. There are several storage schemes possible in a RAID array, each offering a different combination of storage, reliability, and performance. VyOS supports RAID 1 deployments. RAID 1 uses two or more disks that mirror one another to provide system fault tolerance. In a RAID 1 configuration, every sector on one disk is duplicated on every sector of all disks in the array. Provided even one disk in the RAID 1 set is operational, the system continues to run, even through disk replacement (provided that the hardware supports in-service replacement of drives). RAID 1 can be implemented using special hardware or it can be implemented in software. VyOS supports software RAID 1 on two disks. The VyOS implementation of RAID 1 features the following:

  • Detection and reporting of disk failure.

  • Maintain system operation with one failed disk.

  • Boot the system with one failed disk.

  • Replace a failed disk and initiate re-mirroring.

  • Monitor the status of re-mirroring.

Installation implications

The VyOS installation utility provides several options for installing to a RAID 1 set. You can:

  • Use the install system to create the RAID 1 set.

  • Use the built-in Linux commands to create a RAID 1 set before running the install system command.

  • Use a previously-created RAID 1 set.

Note

Before a permanent installation, VyOS runs a live installation.

Configuration

Standard installation on a single disk

VyOS automatically detects the presence of two or more disks that are not currently part of a RAID array when installed. The VyOS installation utility automatically offers you the option to configure RAID 1 mirroring for eligible drives with the following prompt:

Would you like to configure RAID 1 mirroring on them?

  • If you do not want to configure RAID 1 mirroring, enter No at the prompt.

Empty 2+ disk

If VyOS detects two identical disks that are not currently part of a RAID 1 set, the VyOS installation utility automatically offers the option to configure RAID 1 mirroring for the drives with the following prompt:

Would you like to configure RAID 1 mirroring on them?

1. To create a new RAID 1 array, enter Yes at the prompt. If VyOS detects a filesystem on the partitions being used for RAID 1, it will prompt you to indicate whether you want to continue creating the RAID 1 array.

Continue creating array?

  1. To overwrite the old filesystem, enter Yes.

3. The system informs you that all data on both drives will be erased. Confirm you want to continue.

Are you sure you want to do this?

4. Enter Yes at the prompt to retain the current VyOS configuration. Enter No to delete the current VyOS configuration.

Would you like me to save the data on it before I delete it?

5. Enter Yes at the prompt to retain the current VyOS configuration. Enter No to delete the current VyOS configuration.

  1. Continue installing VyOS.

Preexisting RAID 1 configuration

When VyOS detects a previously configured RAID 1 set, the installation utility displays the following prompt:

Would you like to use this one?

1. To break up the current RAID 1 set, enter No at the prompt. The installation utility detects that there are two identical disks and offers you the option of configuring RAID 1 mirroring with the following prompt:

Would you like to configure RAID 1 mirroring on them?

2. To decline to set up a new RAID 1 configuration on the disks, enter No at the prompt. VyOS prompts you to indicate which partition you would like the system installed on.

Which partition should I install the root on? [sda1]:

3. Enter the partition where you would like the system installed. The system then prompts you to indicate whether you want to save the old configuration data. This represents the current VyOS configuration.

Would you like me to save the data on it before I delete it?

4. Enter Yes at the prompt to retain the current VyOS configuration once installation is complete. Enter No to delete the current VyOS configuration.

  1. Continue installing VyOS.

Detecting and replacing a failed RAID 1 disk

VyOS system detects disk failures within a RAID 1 set and reports them to the system console. You can verify the failure by running the show raid command.

To replace a bad disk within a RAID 1 set:

  1. Remove the failed disk from the RAID 1 set:

    delete raid <RAID‐1‐device> member <disk‐partition>

    where RAID-1-device is the name of the RAID 1 device. For example, md0 and disk-partition is the name of the failed disk partition. For example, sdb2.

  2. Physically remove the failed disk from the system. If the drives are not hot-swappable, then you must shut down the system before removing the disk.

  3. Replace the failed drive with a drive of the same size or larger.

  4. Format the new disk for RAID 1 by running the following command:

    format disk <disk‐device1> like <disk‐device2>

    where disk-device1 is the replacement disk. For example, sdb and disk-device2 is the existing healthy disk. For example, sda.

  5. Add the replacement disk to the RAID 1 set by running the following command:

    add raid <RAID‐1‐device> member <disk‐partition>

    where RAID-1-device is the name of the RAID 1 device. For example, md0 and disk-partition is the name of the replacement disk partition. For example, sdb2.

Operation

Learn how to add a disk partition to a RAID 1 set, initiate mirror synchronization, and check and display information.

add raid <RAID‐1‐device> member <disk‐partition>

Use this command to add a member disk partition to the RAID 1 set. Adding a disk partition to a RAID 1 set initiates mirror synchronization, where all data on the existing member partition is copied to the new partition.

format disk <disk‐device1> like <disk‐device2>

This command is typically used to prepare a disk to be added to a preexisting RAID 1 set (of which disk-device2 is already a member).

show raid <RAID‐1‐device>

shows output for show raid md0 as sdb1 is being added to the RAID 1 set and is in the process of being resynchronized.

vyos@vyos:~$ show raid md0
/dev/md0:
      Version : 00.90
Creation Time : Wed Oct 29 09:19:09 2008
   Raid Level : raid1
   Array Size : 1044800 (1020.48 MiB 1069.88 MB)
Used Dev Size : 1044800 (1020.48 MiB 1069.88 MB)
 Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
  Persistence : Superblock is persistent
  Update Time : Wed Oct 29 19:34:23 2008
        State : active, degraded, recovering
Active Devices : 1
Working Devices : 2
Failed Devices : 0
Spare Devices : 1
Rebuild Status : 17% complete
         UUID : 981abd77:9f8c8dd8:fdbf4de4:3436c70f
       Events : 0.103
  Number   Major   Minor   RaidDevice State
     0       8        1        0      active sync   /dev/sda1
     2       8       17        1      spare rebuilding   /dev/sdb1
show disk sda format

Use this command to display the formatting of a hard disk.

vyos@vyos:~$ show disk sda format
Disk /dev/sda: 1073 MB, 1073741824 bytes
85 heads, 9 sectors/track, 2741 cylinders
Units = cylinders of 765 * 512 = 391680 bytes
Disk identifier: 0x000b7179
 Device Boot      Start         End      Blocks   Id  System
/dev/sda1               6        2737     1044922+  fd  Linux raid autodetect