When you install Red Hat Enterprise Linux 7 or one of its offspring, you have the option of encrypting the drive. All you have to do is to click on a checkbox:

Other than that, I just let the installer create the default partitioning scheme, which means that the / filesystem and the swap partition will both be logical volumes. (I'll cover that in a moment.)

Before the installation can continue, I have to create a passphrase to mount the encrypted disk:

Now, whenever I reboot the system, I need to enter this passphrase:

Once the machine is up and running, I can look at the list of logical volumes. I see both the / logical volume and the swap logical volume:

[donnie@localhost etc]$ sudo lvdisplay
  --- Logical volume ---
  LV Path /dev/centos/swap
  LV Name swap
  VG Name centos
  LV UUID tsme2v-uy87-uech-vpNp-W4E7-fHLf-3bf817
  LV Write Access read/write
  LV Creation host, time localhost, 2017-10-28 13:00:11 -0400
  LV Status available
  # open 2
  LV Size 2.00 GiB
  Current LE 512
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 8192
  Block device 253:2

  --- Logical volume ---
  LV Path /dev/centos/root
  LV Name root
  VG Name centos
  LV UUID MKXVO9-X8fo-w2FC-LnGO-GLnq-k2Xs-xI1gn0
  LV Write Access read/write
  LV Creation host, time localhost, 2017-10-28 13:00:12 -0400
  LV Status available
  # open 1
  LV Size 17.06 GiB
  Current LE 4368
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 8192
  Block device 253:1

[donnie@localhost etc]$

And I can look at the list of physical volumes. (Actually, there's only one physical volume in the list, and it's listed as a luks physical volume.):

[donnie@localhost etc]$ sudo pvdisplay
  --- Physical volume ---
  PV Name               /dev/mapper/luks-2d7f02c7-864f-42ce-b362-50dd830d9772
  VG Name               centos
  PV Size               <19.07 GiB / not usable 0
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              4881
  Free PE               1
  Allocated PE          4880
  PV UUID               V50E4d-jOCU-kVRn-67w9-5zwR-nbwg-4P725S

[donnie@localhost etc]$

This shows that the underlying physical volume is encrypted, which means that both the / and the swap logical volumes are also encrypted. That's a good thing, because leaving the swap space unencrypted—a common mistake when setting up disk encryption up manually—can lead to data leakage.