NotesByLex

Red Hat System Administration III - Unit 11 - Centralized and Secure Storage

Lex Toumbourou ·

Linux

Recap of setting up local disks

  • Create partitions:

    > fdisk -cu <device_name>
    • Always reboot after creating parition

    • Create a filesystem:

      mkfs.ext4 /dev/sdb1

  • Create a mount point

    > mkdir /mymount

  • Mount partition

    > mount /mymount /dev/sdb1

  • Create an entry in /etc/fstab

    > vi /etc/fstab
mount  dev_name  fstype  options  <dump_freq>  <fsck 0/1/2>

Accessing iSCSI Storage

  • Targets == Servers
  • Initators == Clients
  • iSCSI Qualified Name (IQN) identifies initiators and targets
    ign.yyyy-mm.{reverse domain}:label

Example

  • Install prereqs:

    > yum install iscsi-initator-utils

  • Discover iSCSI targets

    > iscsiadm -m discovery -t st -p 192.168.0.254
192.168.0.254:3260,1 iqn.2010-09.com.example:rdisks.server2

  • Log on to one or more iSCSI targets

    > iscsiadm -m node -T iqn.2010-09.com.example:rdisks.server2 -l
Logging in to [iface: default, target: iqn.2010-09.com.example:rdisks.server2, portal: 192.168.0.254,3260] (multiple)
Login to [iface: default, target: iqn.2010-09.com.example:rdisks.server2, portal: 192.168.0.254,3260] successful.

  • Check status

    > ls -l /dev/disk/by-path/*iscsi*
lrwxrwxrwx. 1 root root 9 Aug  7 13:36 /dev/disk/by-path/ip-192.168.0.254:3260-iscsi-iqn.2010-09.com.example:rdisks.server2-lun-1 -> ../../sda

  • So, I know that it's using sda as a physical-like disk:

    > fdisk /dev/sda

  • Get UUID of device with:

    > blkid | grep sda
/dev/sda1: UUID="3fa18c35-17bd-4eb3-9409-9a7f211ea8d7" TYPE="ext4"

  • Use UUID to mount within /etc/fstab

    > vi /etc/fstab
+ UUID="3fa18c35-17bd-4eb3-9409-9a7f211ea8d7"     /mnt/iscsi      ext4    _netdev 0 0

  • Then mount it!

    > mkdir /mnt/iscsi
> mount /mnt/iscsi

To remove

  • Log out of iSCSI target

    > iscsiadm -m node -T iqn.2010-09.com.example:rdisks.server2 -p 192.168.0.254 -u
Logging out of session [sid: 1, target: iqn.2010-09.com.example:rdisks.server2, portal: 192.168.0.254,3260]
Logout of [sid: 1, target: iqn.2010-09.com.example:rdisks.server2, portal: 192.168.0.254,3260] successful.

  • Delete the local record of the iSCSI targer

    > iscsiadm -m node -T iqn.2010-09.com.example:rdisks.server2 -p 192.168.0.254 -o delete

Encrypt Centralized Storage

  • Basic procedure:

    • Encrypt device with cryptsetup luksFormat:

      # cryptsetup luksFormat /dev/sda1

    • Open the device with cryptsetup luksOpen and set a passphrase:

      # cryptsetup luksOpen /dev/sda1 secret

    • Create a filesystem:

      # mkfs.ext4

    • Get the UUID with blkid:

      # blkid | grep /dev/mapper/secret

    • Add an entry to crypttab:

      # vi /etc/crypttab
UUID=""     /dev/mapper/secret      (none) or (path-to-passphrase)

    • Add entry in /etc/fstab:

      > vi /etc/fstab
/dev/mapper/secret  /mnt/my_secret  file_system_type _netdev  0 0