notes/hard_disks.md

## RAID edits
* Enter the system setup menu at boot time, then you also have to press additional keys to get to the RAID screen
* create a new virtual disk and assign the new disks, then initialize the VD

## Mounting the new VD
* find the disk with `fdisk -l | grep '^Disk'`
* create a partition table
    * `fdisk /dev/sdb`
    * `p` to list partition table if any
    * `n` to create a new partition
    * `w` to write the new partition
* format the new partition with `mkfs.ext4 /dev/sdb1`
* create an access folder, maybe at //mnt/backup
* run the mount `mount /dev/sdb1 /mnt/backup`
* edit fstab by adding
    * using device name
    ```
    //dev/sdb1  /mnt/backup ext4    defaults    1   2
    ```
    * using UUID (do `sudo blkid` to get the UUID)
    ```
    UUID="86e81045-a0dc-4881-8ddb-5ef25834ea5a" /datadrive  xfs     defaults,nofail 1       2
    ```
* somehow in the process an new systemctl service module is loaded based on fstab at runs at boot

## lvm (logical volume manager)
`vgs` to list volume groups
`vgdisplay` to show all info for a volume group
`lvs` to show logical volumes

Given a logical volume `group` you can extend the size of a `logical volume` inside that group.
```
sudo lvextend -L+100G /dev/ubuntu-vg/ubuntu-lv
```

now if you do `lsblk` the size of the disk has grown but filesystem still needs to be extended as per `df`

use `resize2fs` to expand the file system to take up all the disk space
```
ptrowbridge@usmidsap01:/var/log/postgresql$ sudo resize2fs /dev/ubuntu-vg/ubuntu-lv
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required
old_desc_blocks = 13, new_desc_blocks = 25
The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 52428800 (4k) blocks long.
```