📥 How Writebacks and Snapshots Work in ggRock

This article covers the fundamentals of ggRock’s diskless boot system—specifically, how Writebacks and Snapshots are used to manage changes to your Images.

💾 What Is a Writeback?

A Writeback is a temporary space on the ggRock Array that stores all changes made by a specific Machine since it was started.

When a Machine boots, it receives a fresh, clean copy of the base Image. From there, Windows starts generating files as part of its normal operation—this becomes the Machine’s current state.

Example:

• When you boot PC01 and download the ggLeap installer, that data is stored in PC01's Writeback.
• If you boot PC02, it won’t have the ggLeap installer. That’s because the Writeback from PC01 hasn't been applied to the base Image.
• If you reboot PC01, it will return to a clean state—just like when it first booted.

This means player sessions are isolated—when they reboot, all changes are wiped. 💨

📥 Applying Writebacks

Once you've installed software or made changes you'd like to keep, you can Apply the Writeback:

1. Shut down the Machine.
2. Go to the Machines screen in ggRock.

3. Click Apply Writeback.

💡 This creates a Snapshot—a save point for your Image with the option to roll back later if needed.

You'll be prompted to enter a Comment for the Snapshot (e.g., “Installed ggLeap”). This helps you identify the changes later.

⚠️ You can only apply a Writeback after the Machine is powered off. If you reboot before applying, the changes will be lost!

Once applied, all Machines booting from that Image will now include the changes.

🔁 Keeping Writebacks (Across Reboots)

Some software (like ggLeap) requires a reboot to complete installation. In these cases, you can enable the Keep Writebacks option for that Machine:

• This allows changes to persist across reboots temporarily.
• ⚠️ Note: Machines with Keep Writebacks enabled will not see updates made to the base Image or Snapshots until the option is disabled.

📸 Managing Snapshots

A Snapshot is like a checkpoint or saved version of your Image.

Every time you Apply a Writeback, ggRock automatically creates a new Snapshot. Here's how they work:

🟢 Active Snapshot

• This is the Snapshot that all Machines boot from.
• It's not always the latest, but it’s the one currently in use.

🕓 Latest Snapshot

• The most recently created Snapshot.
• Only Machines booted from the Latest Snapshot are eligible to Apply Writebacks.
• You cannot apply Writebacks from older Snapshots.

Use Snapshots to roll back or test changes without affecting all systems. 👍

🧩 Diagram: How Writebacks and Snapshots Work

The diagram below helps visualize the interaction between Images, Writebacks, and Snapshots:

OS Image (C:\ Drive)

• A layered set of Snapshots forms the complete OS Image.
• Writebacks store all changes made by each Machine (e.g., PC01, PC02, etc.).
• Only the C:\ drive is affected.

Game Image (e.g., G:\ Drive)

• Functions the same way as the OS Image, but for game data.
• Read-only for clients, highly cacheable for performance.

Read/Write Behavior

• Machines read from the ggRock server, often via RAM cache.
• Machines write only to their own isolated Writeback space.

. OS Image

A layered stack of Snapshots that form the base operating system. Snapshots can be removed from any point in the stack, and ggRock intelligently merges the remaining layers to preserve Image integrity while discarding only the data specific to the removed Snapshot.

2. OS Image Writebacks

Each PC automatically generates a Writeback section on the Array when it boots. This section captures all changes made to the C:/ drive by that specific Machine during its session.

3. OS Image Read Operations

Operates identically to Game Image Read Operations, but applies to the OS (C:/ drive) instead.

7. PC-01 Writeback

This Machine reads from the shared OS Image but writes to its own isolated Writeback. All changes made to the C:/ drive by PC-01 during its session are captured here.

8. PC-02 Writeback

Same behavior as PC-01, but specific to PC-02. Reads from the OS Image, writes to its own dedicated Writeback.

9. PC-100 Writeback

Just like PC-01 and PC-02, this Machine reads from the OS Image and logs all C:/ drive changes in its own separate Writeback section.

4. Game Image

Functions like the OS Image, with its own set of Snapshots layered together to form the game data volume.

5. Game Image Writebacks

Just like OS Writebacks, but these store changes made to the G:/ drive (or whichever drive letter is assigned for game data).

6. Game Image Read Operations

All Machines read game data directly from the ggRock server, utilizing RAM cache for maximum performance. No data is written back to the Game Image, allowing for efficient caching of frequently accessed files.

🧪 Diagram: Applying a Writeback

Here’s how applying a Writeback works:

1. PC02 has installed Apex Legends to the OS Image, and those changes are currently stored in its Writeback space (C:/ drive).
2. Same as (1), but for the Game Image—the game data itself is stored in the Game Image Writeback (e.g., G:/ drive).
3. After PC02 is shut down and the Writeback is applied to the OS Image, a new Snapshot is created with the comment "Apex Install."
4. Same as (3), but for the Game Image, capturing game-related changes in its own Snapshot.

Hold Up!

Updated on: 24/12/2025