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disk addition - raid configuration - partitioning
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Linux_Disk.md

Linux Disk

Basic

Note:

nvme0 = disk ( nvme uses PCI interface )
sda   = disk ( sda uses SATA III interface )

nvme0, nvme1 = nvme disk 1,nvme disk 2
sda,sdb,sdc,sdd = disk1,disk2,disk3,disk4

nvme0n1p1 = disk1 partition1
nvme0n1p2 = disk1 partition2

nvme1n1p1 = disk2 partition1
nvme1n1p2 = disk2 partition2


sda1 = disk1 partition1
sdb3 = disk2 partition3
sdc2 = disk3 partition2

md0 = raid
md1 = raid
How to check disk, Partition, Raid?
muhammadshakeeb@test12:~$ lsblk -l
NAME               MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
md0                  9:0    0 255.7M  0 raid1 /boot
md0                  9:0    0 255.7M  0 raid1 /boot
md1                  9:1    0 953.5G  0 raid1
md1                  9:1    0 953.5G  0 raid1
nvme0n1            259:0    0 953.9G  0 disk
nvme0n1p1          259:1    0   256M  0 part
nvme0n1p2          259:2    0 953.6G  0 part
nvme1n1            259:3    0 953.9G  0 disk
nvme1n1p1          259:4    0   256M  0 part
nvme1n1p2          259:5    0 953.6G  0 part

muhammadshakeeb@test23:~$ lsblk -l
NAME       MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda          8:0    0   477G  0 disk
sda1         8:1    0    32G  0 part
sda2         8:2    0   512M  0 part
sda3         8:3    0    40G  0 part
sda4         8:4    0     1K  0 part
sda5         8:5    0 404.4G  0 part
sdb          8:16   0   477G  0 disk
sdb1         8:17   0    32G  0 part
sdb2         8:18   0   512M  0 part
sdb3         8:19   0    40G  0 part
sdb4         8:20   0     1K  0 part
sdb5         8:21   0 404.4G  0 part

root@test34 ~ # lsblk
NAME    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda       8:0    0 953.9G  0 disk
|-sda1    8:1    0    10G  0 part
| `-md0   9:0    0    10G  0 raid1 /boot
|-sda2    8:2    0  16.7G  0 part
| `-md1   9:1    0    50G  0 raid5 /
|-sda3    8:3    0  19.9G  0 part
| `-md2   9:2    0  59.7G  0 raid5
`-sda4    8:4    0 907.3G  0 part
  `-md3   9:3    0   2.7T  0 raid5

How to check disk is SSD or HDD?

cat /sys/block/sda/queue/rotational

If output is 1 then it is HDD if output is 0 then it is SSD.

How to create Partition and set partition table?

muhammadshakeeb@test12:~$ sudo parted /dev/nvme1n1
Model: SAMSUNG MZVLB1T0HBLR-00000 (nvme)
Disk /dev/nvme1n1: 1024GB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags:
(parted) mklabel msdos
(parted) print
Model: SAMSUNG MZVLB1T0HBLR-00000 (nvme)
Disk /dev/nvme1n1: 1024GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start  End  Size  Type  File system  Flags

Above you can see the Partiontable is msdos. Now you need to create 1st partition

(parted) mkpart primary 1049kB 269MB
(parted) print
Model: SAMSUNG MZVLB1T0HBLR-00000 (nvme)
Disk /dev/nvme1n1: 1024GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End    Size   Type     File system  Flags
 1      1049kB  269MB  268MB  primary               lba

Now 2nd partition.

(parted) mkpart primary 269MB 1024GB
(parted) print
Model: SAMSUNG MZVLB1T0HBLR-00000 (nvme)
Disk /dev/nvme1n1: 1024GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  269MB   268MB   primary               lba
 2      269MB   1024GB  1024GB  primary               lba

(parted) quit
Information: You may need to update /etc/fstab.

(parted)
How to check the Raid?

Below basically shows that there are two RAIDS [md0 and md1] ( RAID Level is 1 ) Currently single disk partition is attached on a raid md0 and raid md1.

For RAID 1, you should have two disk ( As it is mirroring )

muhammadshakeeb@test12:~$ sudo cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 nvme0n1p2[0]
      999809344 blocks super 1.2 [2/1] [U_]
      bitmap: 1/8 pages [4KB], 65536KB chunk

md0 : active raid1 nvme0n1p1[0]
      261824 blocks super 1.2 [2/1] [U_]

unused devices: <none>
How to attach a new partition to existing raid?
muhammadshakeeb@redis12:~$ sudo mdadm /dev/md0 --add /dev/nvme1n1p1
mdadm: added /dev/nvme1n1p1
muhammadshakeeb@redis12:~$ sudo mdadm /dev/md1 --add /dev/nvme1n1p2
mdadm: added /dev/nvme1n1p2

To Recheck the process either partition added or not

muhammadshakeeb@redis12:~$ sudo cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 nvme1n1p2[2] nvme0n1p2[0]
      999809344 blocks super 1.2 [2/1] [U_]
      [>....................]  recovery =  0.1% (1001856/999809344) finish=66.4min speed=250464K/sec
      bitmap: 1/8 pages [4KB], 65536KB chunk

md0 : active raid1 nvme1n1p1[2] nvme0n1p1[0]
      261824 blocks super 1.2 [2/2] [UU]

unused devices: <none>

How to install grub if system grub fails after disk replacement?

Some time it happens that grub fails and you are not able to boot the system. Best would be to start the server with liveCD or rescue mode. There are different ways to do that.

To not break anything I have followed below steps

  1. First check the disk structure using lsblk command. In this way you may know where is ROOT and BOOT. If They are in separate disk then you need to follow the steps as below else you can skip: POINT # 2
root@rescue ~ # mkdir /shakeeb/

We have use vg--system-root because it does contain the root partition. you can check using lsblk where is your root and put the same structure for example it is mostly inside: /dev/nvme0n1 or /dev/sda ....

root@rescue ~ # mount /dev/mapper/vg--system-root  /shakeeb
  1. We have mounted /dev/md0 because here it shows a separate disk for BOOT in RAID mode. You can skip it if you have all partition/boot in one disk.
root@rescue ~ # mount /dev/md0 /shakeeb/boot/

  1. Use the proc dev sys files from the rescue mode system. root@rescue ~ # mount --bind /proc /shakeeb/proc root@rescue ~ # mount --bind /dev /shakeeb/dev root@rescue ~ # mount --bind /sys /shakeeb/sys

  2. Once all mounted then you need to switch the mode ( chroot )

root@rescue ~ # chroot /shakeeb /bin/bash
root@rescue / # ls -la
  1. Update grub
root@rescue / # update-grub
  1. If you have two disk ( with BOOT ) then run both the command as below.
root@rescue / # grub-install /dev/nvme0n1
Installing for i386-pc platform.
Installation finished. No error reported.
root@rescue / # grub-install /dev/nvme1n1
Installing for i386-pc platform.
Installation finished. No error reported.
root@rescue / # sync
  1. Exit and then reboot. You can easily access the server then.

How to change the partition type?

Here I am changing the partition type to swap memory. HEX CODE = 82 is for SWAP

root@elk4 ~ # fdisk /dev/sdb3

Welcome to fdisk (util-linux 2.33.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

The old linux_raid_member signature will be removed by a write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x2bad72a0.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 3
First sector (2048-41732095, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-41732095, default 41732095):

Created a new partition 3 of type 'Linux' and of size 19.9 GiB.

Command (m for help): t
Selected partition 3
Hex code (type L to list all codes): 82
Changed type of partition 'Linux' to 'Linux swap / Solaris'.

Command (m for help): w
The partition table has been altered.
Failed to add partition 3 to system: Invalid argument

The kernel still uses the old partitions. The new table will be used at the next reboot.
Syncing disks.


1  lsblk
    2  parted /dev/sdd
    3  apt-get update
    4  apt-get install sudo crypptab parted
    5  apt-get install sudo crypptab
    6  apt-get install sudo cryptab
    7  apt-get install sudo crypttab
    8  apt-get install sudo cryptsetup parted
    9  parted /dev/sda
   10  parted /dev/sdb
   11  parted /dev/sdc
   12  parted /dev/sdd
   13  lsblk
   14  sudo mdadm --create --verbose /dev/md2 --level=5 --raid-devices=4 /dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3
   15  lsblk
   16  sudo mdadm --create --verbose /dev/md3 --level=5 --raid-devices=4 /dev/sda4 /dev/sdb4 /dev/sdc4 /dev/sdd4
   17  lsblk
   18  fdisk /dev/sdd3
   19  fdisk /dev/sdc3
   20  fdisk /dev/sdb3
   21  fdisk /dev/sda3
   22  partprobe /dev/sda
   23  partprobe /dev/sdb
   24  partprobe /dev/sdc
   25  partprobe /dev/sdd
   26  lsblk
   27  mkswap /dev/md2
   28  free -m
   29  swapon -s
   30  free -m
   31  cat /etc/fstab
   32  swapon /dev/md2
   33  free -m
   34  cat /etc/fstab
   35  vim /etc/fstab
   36  sudo init 6
   37  htop
   38  apt-get install htop
   39  htop
   40  lsblk
   41  sudo cryptsetup luksFormat --type luks1 /dev/md126
   42  sudo cryptsetup luksDump /dev/md127
   43  sudo cryptsetup luksDump /dev/md126
   44  vim /etc/crypttab
   45  sudo cryptdisks_start data-crypt
   47  mkfs.ext4 /dev/mapper/data-crypt
   48  ls -la /dev/sd*
   49  ls -la /dev/mapper/
   50  mkdir /data
   51  blkid /dev/mapper/data-crypt
   52  vim /etc/fstab
   53  df -hT
   54  mount -a
   55  df -hT
   56  mount -fa
   57  df -hT
   58  lsblk
   59  cat /etc/crypttab
   60  mount /dev/mapper/data-crypt /data/
   61  df -hT
   62  sudo init 6
   63  lsblk
   64  df -hT
   65  psctl server start
   66  history
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