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Group Quota Calculator

Work out group quota instantly with clear inputs, formula shown and shareable results.

About Group Quota Calculator

Group quotas allocate shared capacity by project rather than by individual, which matches how research and engineering storage is actually consumed. Reserving a share for the largest project and dividing the remainder evenly is the usual starting point; XFS project quotas are generally preferred to group quotas because they follow directory trees rather than file ownership.

Formula

Group allocation

allocatable = size x (1 - reserve); largest group = allocatable x its share; each other group = remainder / (groups - 1)

Worked example

With the default values below, Group Quota Calculator returns Quota for the largest group of 9.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Project groupsminimum 1
24
Filesystem sizeminimum 0.001 TB
40 TB
Share for the largest groupaccepts 0.1–100 %
25 %
Reserve kept unallocatedaccepts 0–60 %
10 %

Results

Quota for the largest group
9.00 TB
Quota for each remaining group
1.17 TB
Allocatable capacity
36.00 TB
Reserved capacity
4.00 TB

Step by step

  1. 1Values used
  2. 2Group allocation
  3. 3Quota for the largest group= 9.00 TB
  4. 4Quota for each remaining group= 1.17 TB
  5. 5Allocatable capacity= 36.00 TB
  6. 6Reserved capacity= 4.00 TB

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 2 decimal places, 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 prefer project quotas over group quotas?

Project quotas apply to a directory tree regardless of who owns the files, which is much closer to how teams think about storage and avoids problems when files are created by service accounts.

How is a group quota enforced when a user is in several groups?

Usage is charged to the file's group ownership, so a setgid directory is essential to ensure files land against the intended project.

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Group Quota Calculator | Calcrivo