qubes-doc/user/advanced-topics/secondary-storage.md

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---
lang: en
layout: doc
permalink: /doc/secondary-storage/
redirect_from:
- /en/doc/secondary-storage/
- /doc/SecondaryStorage/
- /wiki/SecondaryStorage/
ref: 187
title: Secondary Storage
---
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Suppose you have a fast but small primary SSD and a large but slow secondary HDD.
You want to store a subset of your AppVMs on the HDD.
## Instructions
Qubes 4.0 is more flexible than earlier versions about placing different VMs on different disks.
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For example, you can keep templates on one disk and AppVMs on another, without messy symlinks.
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These steps assume you have already created a separate [volume group](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/logical_volume_manager_administration/vg_admin#VG_create) and [thin pool](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/logical_volume_manager_administration/thinly_provisioned_volume_creation) (not thin volume) for your HDD.
See also [this example](https://www.linux.com/blog/how-full-encrypt-your-linux-system-lvm-luks) if you would like to create an encrypted LVM pool (but note you can use a single logical volume if preferred, and to use the `-T` option on `lvcreate` to specify it is thin). You can find the commands for this example applied to Qubes at the bottom of this R4.0 section.
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First, collect some information in a dom0 terminal:
```
sudo pvs
sudo lvs
```
Take note of the VG and thin pool names for your HDD, then register it with Qubes:
```shell_session
# <pool_name> is a freely chosen pool name
# <vg_name> is LVM volume group name
# <thin_pool_name> is LVM thin pool name
qvm-pool --add <pool_name> lvm_thin -o volume_group=<vg_name>,thin_pool=<thin_pool_name>,revisions_to_keep=2
```
Now, you can create qubes in that pool:
```
qvm-create -P <pool_name> --label red <vmname>
```
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It isn't possible to directly migrate an existing qube to the new pool, but you can clone it there, then remove the old one:
```
qvm-clone -P <pool_name> <sourceVMname> <cloneVMname>
qvm-remove <sourceVMname>
```
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If that was a template, or other qube referenced elsewhere (NetVM or such), you will need to adjust those references manually after moving.
For example:
```
qvm-prefs <appvmname_based_on_old_template> template <new_template_name>
```
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In theory, you can still use file-based disk images ("file" pool driver), but it lacks some features such as you won't be able to do backups without shutting down the qube.
### Example HDD setup
Assuming the secondary hard disk is at /dev/sdb (it will be completely erased), you can set it up for encryption by doing in a dom0 terminal (use the same passphrase as the main Qubes disk to avoid a second password prompt at boot):
```
sudo cryptsetup luksFormat --hash=sha512 --key-size=512 --cipher=aes-xts-plain64 --verify-passphrase /dev/sdb
sudo blkid /dev/sdb
```
Note the device's UUID (in this example "b209..."), we will use it as its luks name for auto-mounting at boot, by doing:
```
sudo nano /etc/crypttab
```
And adding this line (change both "b209..." for your device's UUID from blkid) to crypttab:
```
luks-b20975aa-8318-433d-8508-6c23982c6cde UUID=b20975aa-8318-433d-8508-6c23982c6cde none
```
Reboot the computer so the new luks device appears at /dev/mapper/luks-b209... and we can then create its pool, by doing this on a dom0 terminal (substitute the b209... UUIDs with yours):
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First create the physical volume
```
sudo pvcreate /dev/mapper/luks-b20975aa-8318-433d-8508-6c23982c6cde
```
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Then create the LVM volume group, we will use for example "qubes" as the <vg_name>:
```
sudo vgcreate qubes /dev/mapper/luks-b20975aa-8318-433d-8508-6c23982c6cde
```
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And then use "poolhd0" as the <thin_pool_name> (LVM thin pool name):
```
sudo lvcreate -T -n poolhd0 -l +100%FREE qubes
```
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Finally we will tell Qubes to add a new pool on the just created thin pool
```
qvm-pool --add poolhd0_qubes lvm_thin -o volume_group=qubes,thin_pool=poolhd0,revisions_to_keep=2
```
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By default VMs will be created on the main Qubes disk (i.e. a small SSD), to create them on this secondary HDD do the following on a dom0 terminal:
```
qvm-create -P poolhd0_qubes --label red unstrusted-hdd
```