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OVH Setup server hybrid second disk array

As OVH doesn’t provide a guide to install the second disk array, which is sold optionally, I will publish my solution.

Please be careful, only try these on test configurations and without any disks containing critical data. Some commands can destroy all of your data.

There seems to be soon a solution within the manager – but for now this isn’t working:

Tested on Ubuntu 14.04

Some commands to detect your actual configuration:

    fdisk -l
    lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
    df -h -x devtmpfs -x tmpfs

Delete sdb1/sda1 with parted:

    parted /dev/sdb
    (parted) print
    Model: ATA HGST HUS726040AL (scsi)
    Disk /dev/sdb: 4001GB
    Sector size (logical/physical): 512B/512B
    Partition Table: gpt
 
    Number  Start   End    Size   File system  Name     Flags
     1      1049kB  537MB  536MB               primary  boot
 
    (parted) rm 1
    (parted) quit
 
 
    parted /dev/sda
    (parted) print
    Model: ATA HGST HUS726040AL (scsi)
    Disk /dev/sda: 4001GB
    Sector size (logical/physical): 512B/512B
    Partition Table: gpt
 
    Number  Start   End    Size   File system  Name     Flags
     1      1049kB  537MB  536MB               primary  boot
 
    (parted) rm 1
    (parted) quit

Add new raid partition (needs to be done for sdb and sda):

    # Create raid 1 in live linux system
    parted -a optimal /dev/sdb
    # Place a flag gpt or mbr
    mklabel gpt
    # Create partition
    mkpart primary ext4 0% 100%
    # Mark partition as software raid partition
    set 1 raid on
    # Verify its alligned
    align-check
    optimal
    # Show results
    print
 
    # Create raid 1 in live linux system
    parted -a optimal /dev/sda
    # Place a flag gpt or mbr
    mklabel gpt
    # Create partition
    mkpart primary ext4 0% 100%
    # Mark partition as software raid partition
    set 1 raid on
    # Verify its alligned
    align-check
    optimal
    # Show results
    print

Create new raid configuration (‘level’ can be used for RAID0/1/5 …):

    mdadm --create --verbose /dev/md4 --level=0 --assume-clean --raid-devices=2 /dev/sdb1 /dev/sda1
    cat /proc/mdstat

In case of renaming:

    # Delete all and rescan
    mdadm -Ss
    mdadm --assemble --verbose /dev/md4 /dev/sdb1 /dev/sda1

Update mdadm configuration:

    # NOT NECCESSAIRE MAYBY USEFUL
    # mdadm --monitor --daemonise /dev/md4
 
    # Capture output
    mdadm --detail --scan
    # Something like: 'ARRAY /dev/md4 UUID=7d45838b:7886c766:5802452c:653f8cca'
    # Needs to be added to the end of file:
    /etc/mdadm/mdadm.conf
 
    # Update initramfs (ignore errors):
    update-initramfs -v -u
 
    # Create file system: 
    mkfs.ext4 -F /dev/md4
 
    # Mount fs:
    mount /dev/md4 /opt/
 
    # Update fstab:
    /etc/fstab
    /dev/md4 	/opt	ext4	defaults 	0	1

Could look something like that:

    lsblk
 
    NAME        MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
    sdb           8:16   0   3.7T  0 disk
    `-sdb1        8:17   0   3.7T  0 part
      `-md4       9:4    0   7.3T  0 raid0 /opt
    nvme1n1     259:0    0 419.2G  0 disk
    |-nvme1n1p3 259:3    0   5.4G  0 part  [SWAP]
    |-nvme1n1p1 259:1    0   511M  0 part
    `-nvme1n1p2 259:2    0 413.3G  0 part
      `-md2       9:2    0 413.3G  0 raid1 /
    sda           8:0    0   3.7T  0 disk
    `-sda1        8:1    0   3.7T  0 part
      `-md4       9:4    0   7.3T  0 raid0 /opt
    nvme0n1     259:4    0 419.2G  0 disk
    |-nvme0n1p3 259:7    0   5.4G  0 part  [SWAP]
    |-nvme0n1p1 259:5    0   511M  0 part  /boot/efi
    `-nvme0n1p2 259:6    0 413.3G  0 part
      `-md2       9:2    0 413.3G  0 raid1 /

Now you can reboot the server and verify your configuration.

https://doc.ubuntu-fr.org/raid_logiciel
https://www.psylogical.org/node/198
https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-16-04
https://github.com/etalab/etalab-support/tree/master/procedures
https://docs.ovh.com/fr/dedicated/raid-soft/

2019
02/13
CATEGORY
Administration
Bash
Cloud
Lunix
Testing
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Preseed apt_get for unattended_installs

Installation of some packages require user input, which breaks the entire concept of “unattended” installs. Here’s a quick fix to get around that.

First, on a setup computer, install the following:

sudo apt-get install debconf-utils

Now, install whatever packages you wish to later install in an unattended mode. Answer the questions for installation appropriately when prompted. Next we will export those answers into a “seed” file that we can use when installing the package on a new machine. For instance, I’ve installed several ldap authentication packages, so I might want to grab all of the settings those packages ask for.

sudo debconf-get-selections | grep ldap > ldap.seed

If you remember from yesterday, we created an archive that included a setup script and several config files. Place the ldap.seed file inside that archive along with the other scripts, and just before doing the apt-get install add the following line to the add2network.sh file:

debconf-set-selections ./ldap.seed

And there you have it – your apt-get won’t ask for details anymore.

Source: ossramblings

2018
06/07
CATEGORY
Bash
Lunix
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MySql JSON support!

JSON support. Beginning with MySQL 5.7.8, MySQL supports a native JSON type. JSON values are not stored as strings, instead using an internal binary format that permits quick read access to document elements. JSON documents stored inJSON columns are automatically validated whenever they are inserted or updated, with an invalid document producing an error. JSON documents are normalized on creation, and can be compared using most comparison operators such as =,<, <=, >, >=, <>, !=, and <=>; for information about supported operators as well as precedence and other rules that MySQL follows when comparing JSON values, see Comparison and Ordering of JSON Values.

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MySQL 5.7.8 also introduces a number of functions for working with JSON values. These functions include those listed here:

Image result for json

In MySQL 5.7.9 and later, you can use column->path as shorthand for JSON_EXTRACT(column, path). This works as an alias for a column wherever a column identifier can occur in an SQL statement, including WHERE, ORDER BY, and GROUP BY clauses. This includes SELECT, UPDATE, DELETE, CREATE TABLE, and other SQL statements. The left hand side must be a JSON column identifier (and not an alias). The right hand side is a quoted JSON path expression which is evaluated against the JSON document returned as the column value.

See Section 12.16.3, “Functions That Search JSON Values”, for more information about -> and JSON_EXTRACT(). For information about JSON path support in MySQL 5.7, see Searching and Modifying JSON Values. See also Secondary Indexes and Virtual Generated Columns.

2015
12/02
CATEGORY
JavaScript
MySql
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