Archive Notice

This page is just a general guide, and doesn't directly relate to the source files of the project.

Backups to Local USB Devices

Basically, to big external USB HDDs.

Overview

• Start with a wiped hard drive.
• Add a partition table and file system.
• Mount the file system.
• Create a PVE storage entry to point to the file system.
• Pitfalls and Troubleshooting.

Find the Wiped Hard Drive

It shouldn't be mounted anywhere, and shouldn't have any sub-entries (partitions). In this example, it's a 4 TB external hard drive, sdb.

root@pve1:~# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                            8:0    0 136.8G  0 disk
├─sda1                         8:1    0  1007K  0 part
├─sda2                         8:2    0   512M  0 part /boot/efi
└─sda3                         8:3    0 136.2G  0 part
  ├─pve-root                 253:0    0    34G  0 lvm  /
  ├─pve-swap                 253:1    0     7G  0 lvm  [SWAP]
  ├─pve-data_tmeta           253:2    0     1G  0 lvm
  │ └─pve-data               253:4    0  77.2G  0 lvm
  └─pve-data_tdata           253:3    0  77.2G  0 lvm
    └─pve-data               253:4    0  77.2G  0 lvm
sdb                            8:16   0   3.7T  0 disk

Partition Table and File System

Use fdisk to create.

# fdisk /dev/sdb

Welcome to fdisk (util-linux 2.29.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
The size of this disk is 3.7 TiB (4000787029504 bytes). DOS partition table format can not be used on drives for volumes larger than 2199023255040 bytes for 512-byte sectors. Use GUID partition table format (GPT).

Created a new DOS disklabel with disk identifier 0xa3f7f1b7.

Command (m for help): g
Created a new GPT disklabel (GUID: 5794B3D2-112B-4459-BEC6-F614CE19B3DF).

Command (m for help): n
Partition number (1-128, default 1):
First sector (2048-7814037133, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-7814037133, default 7814037133):

Created a new partition 1 of type 'Linux filesystem' and of size 3.7 TiB.

Command (m for help): p
Disk /dev/sdb: 3.7 TiB, 4000787029504 bytes, 7814037167 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
Disklabel type: gpt
Disk identifier: 5794B3D2-112B-4459-BEC6-F614CE19B3DF

Device     Start        End    Sectors  Size Type
/dev/sdb1   2048 7814037133 7814035086  3.7T Linux filesystem

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Use lsblk to make sure it worked as expected.

# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
[sda stuff]
sdb                            8:16   0   3.7T  0 disk
└─sdb1                         8:17   0   3.7T  0 part

Mount the File System

# mkdir /media/big-usb
# mount /dev/sdc1 /media/big-usb/

# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
[sda stuff]
sdb                            8:16   0   3.7T  0 disk
└─sdb1                         8:17   0   3.7T  0 part /media/big-usb

Create the PVE Storage Entry

This example is configured to store a maximum of 7 backup images for each VM. Add the following entry to the existing ones. Do not delete the other entries in the storage.cfg file!

# nano /etc/pve/storage.cfg

[other entires - KEEP]

dir: big-usb-backup
        path /media/big-usb/
        content backup
        maxfiles 7
        shared 0

Pitfalls and Troubleshooting

This setup isn't a "once-and-done" type thing. Some steps need to be manually re-done each time. The negative impacts of each one are detailed here.

Forgetting to Mount the USB Device

The result here is that the backups will be saved to the local hard drive. The one that the OS is installed on.

If the backup files are small this could go unnoticed. In case the OS boot drive were to fail, all the backups would be lost.

If they were larger, I assume a "no free space error" would happen.

Forgetting to Create the Mount Directory

Not creating /media/big-usb has the exact same effect as the section above.

That's because PVE auto creates the directory (if it doesn't exist) once the dir: big-usb-backup entry is added to storage.cfg.

The net effect is, once again, that files are saved to the local OS hard drive.