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Log Retention For Compliance Calculator

Work out log retention for compliance instantly with clear inputs, formula shown and shareable results.

About Log Retention For Compliance Calculator

Compliance regimes set retention floors — PCI DSS requires a year with three months immediately available, and several regulators require longer — which naturally produces a two-tier design. The hot tier is sized for investigation and stays uncompressed and indexed; the cold tier holds the remainder compressed, typically at 5 to 10 times, at a fraction of the cost per gigabyte.

Formula

Log storage

hot = daily volume x hot days; cold = daily volume x cold days / compression ratio; total = hot + cold

Worked example

With the default values below, Log Retention For Compliance Calculator returns Total log storage of 30.84 TiB. Change any input above and every figure here is recalculated in your browser.

Inputs used

Log volume per dayminimum 0.01 GB
250 GB
Hot / searchable retentionminimum 1 days
90 days
Cold / archive retentionminimum 0 days
365 days
Archive compression ratioaccepts 1–50 x
8 x

Results

Total log storage
30.84 TiB
Hot searchable tier
20.46 TiB
Compressed archive tier
10.37 TiB
Total retention period
455 days

Step by step

  1. 1Values used
  2. 2Log storage
  3. 3Total log storage= 33,906,250,000,000
  4. 4Hot searchable tier= 22,500,000,000,000
  5. 5Compressed archive tier= 11,406,250,000,000
  6. 6Total retention period= 455 days

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 whole numbers, 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

What retention does PCI DSS require?

At least 12 months of audit log history, with a minimum of three months immediately available for analysis, which is exactly the hot and cold split.

Does index overhead need to be added?

Yes for the hot tier. Search indexes commonly add 10 to 50 percent on top of raw volume depending on the platform and field extraction.

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