Blender 3D and Disk Caching Explained

Blender is one of the most disk-heavy creative applications on Windows. It reads large .blend files on every save and undo, writes cache files for simulations and renders, and keeps a viewport preview cache that grows over a session.

This guide explains what Blender stores, how each cache behaves, and what is worth accelerating with a disk cache.

PAGE CONTENT

• What Blender Stores on Disk
• How Blender Caches Behave
• How They Interact with a Disk Cache
• Where the Two Conflict
• Configure a Cache for Blender
• FAQs About Blender and Caching
• Back Up Windows Before You Change Settings

What Blender Stores on Disk

Blender produces several different kinds of disk files, and each has a different access pattern:

• The .blend file. The scene file itself, which can be hundreds of megabytes and is read on every open, undo, and save.
• Simulation caches. Fluid, smoke, cloth, and particle simulations write .bphys and .vdb files that are read back on every playback - the pattern described in caching for 3D rendering.
• Render output. Frames are written sequentially during a render, which is streaming write work.
• The viewport preview cache. Blender keeps cached images of the viewport for quick scrubbing, stored under the temp folder.
• Packed assets. Textures and linked libraries can be packed into the blend file or kept as external files, which changes the read pattern.

How Blender Caches Behave

The access pattern is a mix of large sequential files and small scattered reads, which is what makes it interesting:

• .blend reads are large and repetitive. Every undo step reads the same scene file, which is exactly the pattern a cache is built for.
• Simulation caches are read on every playback. A fluid sim that took hours to bake is read in seconds during playback, and the same files are read every time you scrub the timeline.
• Render writes are sequential and one-pass. A frame is written once and never read again by the renderer, which is the case where caching cannot help - see when a disk cache does not help.
• The viewport cache is small and hot. A few hundred megabytes of preview images are read constantly while scrubbing.
• Temp files are written and deleted. Autosaves and render intermediates are short-lived, which is closer to buffering than caching - see cache vs buffer.

How They Interact with a Disk Cache

The two layers stack well because Blender's reads are exactly what a disk cache is good at:

• Undo hits the cache. Every undo reads the same scene file, which the RAM tier serves after the first read.
• Simulation playback hits the cache. The same .bphys and .vdb files are read on every timeline scrub, which the cache holds easily.
• Large textures benefit from the SSD tier. A texture pack that does not fit in RAM is still faster from the SSD tier than from the raw drive.
• Render writes pass through. A disk cache cannot make rendering faster, but it can absorb the writes so they do not interrupt reads - the distinction is in write caching vs read caching.
• The viewport cache stays in RAM. It is small enough that the RAM tier holds it permanently during a session.

Where the Two Conflict

A few setups work against each other, and they are easy to avoid:

• Putting the temp folder on a RAM disk. Blender writes large render intermediates to temp, which can overflow a small RAM disk - see moving the temp folder to a RAM disk.
• Caching the render output folder. Render frames are written once and never read by the renderer, so caching them wastes space.
• Storing simulations on a network drive. Network reads cannot be helped by a local disk cache, and playback becomes choppy under load.
• Caching a folder that is about to be cleared. If Blender clears its temp cache at exit, the disk cache learns blocks that are deleted a moment later.
• Running a bake and a render at the same time. A simulation bake writes huge files while the render reads the scene, and both compete for the cache.

Quick summary

Blender is one of the best candidates for a disk cache. Undo and simulation playback are the wins; render output is not.

Configure a Cache for Blender

The cleanest setup is to point a disk cache at the volume that holds your .blend files and simulation caches, and let the RAM tier hold the scene file and viewport preview. Qiling Fast Cache uses a RAM tier for the hottest blocks and an SSD tier for the rest, and shows the hit rate in the task list.

• Free Download
• Windows 11/10/8/7, 100% Secure

Step 1. Install Qiling Fast Cache and open the task list. Open your largest .blend file once before configuring anything.

Step 2. Click the "+" button and select the volume that holds your .blend files and simulation caches, not the render output folder.

Step 3. Size the SSD tier for your largest scene file plus its simulation caches, which is usually a few gigabytes.

Step 4. Work in Blender for an hour, including undo and timeline scrubbing, then read the hit rate - see how to check cache hit rate - and confirm that scene reads are being served from the RAM tier.

FAQs About Blender and Caching

Will a disk cache make rendering faster?

No. Rendering is bounded by the GPU or CPU, not the disk. The cache helps undo and playback, not the render itself.

Should I put the Blender temp folder on a RAM disk?

Only if it is large enough. Render intermediates can be several gigabytes, and a small RAM disk will overflow.

Why does undo feel slow sometimes?

The scene file is being read from disk. A disk cache serves it from the RAM tier on the second undo and afterwards.

Should I cache the render output folder?

No. Render frames are written once and never read by the renderer, so caching them wastes space.

Does a cache help simulation playback?

Yes, significantly. The same cache files are read on every timeline scrub, which is exactly what the RAM tier is for.

Back Up Windows Before You Change Settings

Reconfiguring storage and cache settings is easier to undo when you have a recent image. Qiling Disk Master creates a full Windows backup you can restore from.

• Free Download
• Windows 11/10/8/7, 100% Secure

Part 1: Create a Full System Backup

Step 1. Install and open Qiling Disk Master. On the home screen, open "Backup and Recovery" and choose "System Backup". This option automatically includes Windows and the hidden boot partitions, so you do not have to select them one by one.

Step 2. Check the source. The disk where Windows is installed and its system partitions are already ticked for you. If you only need your personal documents, run a separate "File Backup" task instead.

Step 3. Click the destination box and choose where the image should be saved. Use an external HDD or SSD, a NAS, or any drive other than the one Windows is installed on, and make sure it has enough free space.

Step 4. Review the task summary and click "Proceed". Wait until the progress bar reaches 100%. Do not unplug the drive or turn off the PC while the backup is running.

Part 2: Restore Windows from the Backup

Step 1. Open Qiling Disk Master again, go to "Backup and Recovery", and select the recovery option. Your backup images are listed, so pick the one you created before the changes began.

Step 2. Choose the target disk or partition. Normally you restore to the original system disk. If the drive was replaced, select the new disk instead, and the restore rebuilds Windows together with its boot partitions.

Step 3. Preview the restore plan, click "Proceed", and confirm the warning. The PC restarts to finish the job, and Windows comes back exactly as it was on the day the image was created.

Conclusion

Blender is one of the best candidates for a disk cache. Undo reads the same scene file repeatedly, simulation playback reads the same cache files on every timeline scrub, and the viewport preview is small enough to sit in the RAM tier permanently. The cache cannot make rendering faster because that is bounded by the GPU, and it cannot help render output because frames are written once. Point the cache at the volume that holds your .blend files and simulation caches, size the SSD tier for the scene plus its bakes, and read the hit rate after an hour of real work rather than assuming the render folder needs special treatment.

Protect your PC with Qiling Backup—create a system image before your next round of settings changes.

For more creative and caching guides, see caching for 3D rendering, caching for CAD software, RAM disk for video editing, RAM disk for Photoshop scratch disk, and caching for music production.

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  Another creative workload that reads large project files repeatedly.
• Disk Caching for Data Analysis
• Disk Caching for IDE Indexing
• Disk Caching for Game Development
• Disk Caching for Console Emulators

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