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Docker Storage Driver Overhead Calculator

Compare overlay2, aufs and devicemapper storage driver overhead for your workload.

About Docker Storage Driver Overhead Calculator

Docker storage drivers (overlay2, aufs, devicemapper) manage how image layers are stored and shared. overlay2 has minimal overhead (~2%), aufs slightly more (~5%), and devicemapper uses block-level copy-on-write with higher metadata overhead (~12%). Total disk = image × (1 + overhead) + containers × writable_layer.

Formula

Total Disk

totalDisk = image × (1 + overheadFactor) + containers × writableLayer

image
Image size in MB
overheadFactor
Driver-specific overhead (0.02–0.12)
writableLayer
Average writable layer per container

Worked example

With the default values below, Docker Storage Driver Overhead Calculator returns Total Disk Usage of 1,510.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Image Sizeaccepts 1–100,000 MB
500 MB
Running Containersaccepts 1–10,000 containers
20 containers
Avg Writable Layer per Containeraccepts 0–50,000 MB
50 MB
Storage Driverone of overlay2, aufs, devicemapper
overlay2

Results

Total Disk Usage
1,510.0 MB
Storage Driver Overhead
10.0 MB
Total Writable Layers
1,000 MB
Shared Image Disk
510.0 MB

Step by step

  1. 1Driver overhead on image= 10.0MB
  2. 2Shared image on disk (image + overhead)= 510.0MB
  3. 3Total writable layers= 1000MB
  4. 4Total disk usage= 1510.0MB

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is overlay2 recommended?

overlay2 uses efficient page-level copy-on-write directly on modern kernels (4.0+), has minimal metadata overhead, and is the default in all modern Docker installations.

When would devicemapper still be relevant?

On older RHEL/CentOS systems without overlay filesystem support, devicemapper (direct-lvm mode) was the only production-ready option, but it has been deprecated in favor of overlay2.

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