In the vast realm of virtualization, Proxmox VE stands out as a robust, open-source solution that many IT professionals and hobbyists alike have come to rely on. But beneath its user-friendly interface lies every Proxmox user’s crucial decision: choosing the right filesystem.

This choice can influence performance, data integrity, and how we manage our virtual machines. For those new to Proxmox, the terms ‘EXT4’ and ‘ZFS’ might sound like cryptic code.

Proxmox filesystems

Fear not! In this article, I’ll demystify these filesystems, breaking them down in a way that’s easy to grasp, even if you’re dipping your toes into the world of Proxmox.

Whether you’re setting up your first Proxmox server or looking to optimize your existing setup, understanding these filesystems is a step you won’t want to skip.

Selecting the appropriate Proxmox filesystems is a crucial aspect of the initial setup process. It is essential to have a solid understanding in order to make informed decisions that align with your needs and requirements.

Please read my article about Proxmox Server install. Where I describe both scenarios installing Proxmx with a hardware and software raid.

Proxmox filesystems choice

EXT4 Filesystem: A Beginner’s Overview

What is EXT4?

  • EXT4 stands for “Fourth Extended Filesystem.” It’s like a digital filing cabinet for your computer where you store all your data. Just as you have different models and brands of filing cabinets, computers have different types of filesystems, and EXT4 is one of them.

Why is it popular?

  • Maturity & Stability: EXT4 has been around for a while and is a direct successor to the EXT3 filesystem. It’s tried, tested, and trusted by many Linux users.
  • Widely Supported: Most Linux distributions, including the underlying system of Proxmox, support EXT4. This means getting help or finding resources online is easy if you encounter issues.

Key Features:

  1. Journaling: Imagine you’re writing a letter, and suddenly the power goes out. Without saving, you might lose that letter. Journaling is like an automatic save feature. It keeps a log of changes to recover your data if something goes wrong (like a power outage).
  2. Large File & Filesystem Support: EXT4 can handle very large files (up to 16 TiB) and large volumes (up to 1 EiB). This is more space than most users will ever need!
  3. Subdirectories: You can have a large number of subdirectories, up to 64,000, which is great for organization.

Why use EXT4 with Proxmox?

  • Simplicity: For beginners, EXT4 offers a straightforward setup without too many bells and whistles. It’s like choosing a basic model of a car when you’re learning to drive.
  • Compatibility: Since Proxmox is based on Debian Linux, and EXT4 is widely supported in the Linux world, you’ll have fewer compatibility issues.
  • Performance: While it might not have all the advanced features of newer filesystems, EXT4 is reliable and offers good performance for standard use cases.


  • Advanced Features: EXT4 doesn’t have some of the advanced features like snapshots or data deduplication that other filesystems like ZFS offer. It’s like having a car without luxury features – it’ll get you from point A to B, but without the added perks.

In summary, if you’re a Proxmox beginner and looking for a reliable, well-supported, and straightforward filesystem, EXT4 is a solid choice. As you become more familiar with Proxmox and its needs, you can explore other filesystems that offer more advanced features.

ZFS Filesystem: A Beginner’s Overview

What is ZFS?

  • ZFS stands for “Zettabyte File System.” Think of it as a high-tech, advanced digital filing cabinet for your computer. Unlike traditional filing cabinets, ZFS is like a smart cabinet that can automatically organize, repair, and protect your files.

Why is it popular, especially with Proxmox?

  • All-in-One Solution: ZFS isn’t just a filesystem; it’s also a volume manager. This means it handles both how data is stored (like the drawers in a filing cabinet) and how it’s organized (like the folders inside the drawers).
  • Advanced Features: ZFS comes with a suite of powerful features that are especially useful for virtualization platforms like Proxmox.

Key Features:

  1. Snapshots & Clones: Imagine taking a photo of your entire filing cabinet’s contents at a specific moment. That’s a snapshot. If you want to create a duplicate cabinet based on that photo, that’s a clone. This is super useful for backups and testing.
  2. Data Integrity: ZFS constantly checks your data to ensure it hasn’t been accidentally damaged. If it finds any issues, it can automatically repair them using a feature called “checksums.”
  3. Compression & Deduplication: ZFS can automatically shrink your files to save space (compression) and ensure you don’t have unnecessary duplicates (deduplication).
  4. RAID Capabilities: ZFS can combine multiple hard drives in various configurations to either boost performance, provide data redundancy, or both.

Why use ZFS with Proxmox?

  • Reliability: With its data integrity features, ZFS ensures that your virtual machines and containers are safe from data corruption.
  • Performance: ZFS can utilize caching mechanisms, like the Adaptive Replacement Cache (ARC), to speed up data access.
  • Flexibility: The snapshot and cloning features make it easy to backup, replicate, or test changes in your Proxmox environment.

Does ZFS need a lot of RAM? Why?

  • Yes, it does. ZFS is fast and efficient because of its caching mechanisms, especially the ARC (Adaptive Replacement Cache). The ARC stores frequently accessed data in RAM to retrieve it quickly. The more RAM you have, the larger the ARC can be, leading to better performance.
  • Deduplication: If you enable deduplication (a feature that ensures only one copy of duplicate data is stored), it can consume a significant amount of RAM. This is because ZFS needs to keep a table in memory of all the unique chunks of data.


For a typical Proxmox setup using ZFS, it’s often recommended to have at least 16GB of RAM, with 32GB or more ideal, especially if running multiple VMs or containers. If you’re using deduplication, you’ll need even more.

In summary, ZFS is a powerful and advanced filesystem well-suited for Proxmox. While it has higher RAM requirements than other filesystems, its data integrity, performance, and flexibility benefits often outweigh the drawbacks for many Proxmox users.

Other Proxmox filesystems

LVM with Thin Provisioning:

  • Description: Logical Volume Manager (LVM) allows for flexible disk management, and when combined with thin provisioning, it can allocate storage on an as-needed basis.
  • Pros:
    • Flexible disk management.
    • Can overcommit storage, meaning you can allocate more virtual storage than you have physical storage (use with caution).
    • Supports snapshots.
  • Cons:
    • Overcommitting storage can lead to issues if physical storage runs out.
    • Doesn’t have the extensive feature set or data integrity checks of ZFS.

4. Ceph:

  • Description: While not a traditional filesystem like the others, Ceph is a distributed storage system that Proxmox can use.
  • Pros:
    • Scalable and can distribute data across multiple servers.
    • Provides redundancy and high availability.
    • Integrated into Proxmox for use as storage for VMs and containers.
  • Cons:
    • More complex to set up than local storage options.
    • Requires a minimum of three nodes for a proper setup.

Here is a short table with all available Proxmox filesystems. Above, I mentioned only the Proxmox filesystems, which are more common.

EXT4A widely-used journaling filesystem in Linux.
ZFSAdvanced filesystem with built-in volume management. Known for data integrity and advanced features like snapshots.
LVMLogical Volume Manager for flexible disk management. Can be combined with thin provisioning.
CephDistributed storage system suitable for clustered setups.
NFSNetwork File System for file sharing in networked setups.
iSCSIProtocol for block-level data storage over IP networks.
GlusterFSScalable network filesystem for data-intensive tasks.
BtrfsModern filesystem with features like snapshots, though less common in Proxmox compared to ZFS.

While Proxmox supports multiple storage solutions and filesystems, the best choice often depends on the specific needs of the user, the hardware setup, and the desired features.

Proxmox Filesystems Decoded: Final Insights for the Beginner

Navigating the world of Proxmox can be a rewarding journey, offering a blend of power and flexibility that few virtualization platforms can match. Central to this experience is the choice of a filesystem, a decision that can significantly influence your Proxmox environment’s performance and reliability.

While EXT4 and ZFS have their merits for beginners, ZFS stands out with its advanced features like snapshots, data integrity checks, and built-in RAID capabilities. However, a crucial point to remember is that ZFS is designed to manage the disks directly and doesn’t play well with hardware RAID controllers. This is because ZFS relies on having direct access to the disk to ensure data integrity and perform its advanced functions. Using it with a hardware RAID controller can negate some of its benefits and even lead to data corruption in certain scenarios.

My recommendation for the Proxmox filesystems

For those just starting with Proxmox, if your server or setup includes a hardware RAID controller, it might be best to stick with EXT4 or consider bypassing the RAID functions and giving ZFS direct disk access. On the other hand, if you’re setting up a new environment or have the flexibility to choose, opting for ZFS without hardware RAID can provide a robust and feature-rich experience, making the most of what Proxmox offers.

Remember, the journey with Proxmox is as much about learning as it is about implementation. Take the time to understand your needs, your hardware, and the implications of your choices. With the right knowledge, you’ll be well-equipped to create a virtual environment that’s both efficient and resilient.

Did my article assist you in gaining mastery over the diverse array of choices presented by Proxmox filesystems? Leave a comment below or send me an email to [email protected]. I would love to hear about your experience with Proxmos.

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