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Veeam Capacity Calculator

The calculator helps estimate the storage required for:

  • Veeam Cloud Connect
  • Veeam Cloud Connect Hardened
  • Cloud4You OCS for Veeam

Capacity sizing calculator

The result is an estimate intended for capacity planning.

Actual storage usage depends on the data characteristics, compression, deduplication, Daily Change Rate, backup schedules, and the behavior of the specific job.

STEP 1

Data parameters

Total size of data protected by backup before compression and deduplication.
%
Expected data reduction after compression and deduplication.
%
Average portion of data changed between consecutive backups.
STEP 2

Retention and data protection

days
Number of days for which restore points should be retained.
/ day
For a typical Backup Copy Job, leave the value at 1.
By default, the calculator assumes a weekly chain of Full + 6 Incremental.
days
Used for Synthetic Full and Active Full.
Advanced settings
%
%

How does the calculator size Veeam Cloud Connect?

For the full backup and increment, we use the same basic assumptions as in the Veeam calculator example:

Source data:        10 TB
Compression/reduction: 50%
Daily Change Rate:   5%

which gives:

Full:
10 TB × 50%
= 5 TB

Increment:
10 TB × 5% × 50%
= 0.25 TB

Forward Incremental + weekly Full

With a Full created every 7 days, one complete chain uses:

1 × Full
+
6 × Incremental

Sizing must also include the next chain required during retention rotation.

For 14-day retention:

ceil(14 / 7) + 1
= 3 chains

that is:

3 × Full
18 × Incremental

The calculator also adds:

Working space = 1 × Full + 1 × Incremental

For the 10 TB / 50% / DCR 5% example:

3 × 5 TB       = 15.00 TB
18 × 0.25 TB   =  4.50 TB
Working space  =  5.25 TB
-------------------------
Total          = 24.75 TB

After rounding:

24.8 TB

which is the same as the Veeam calculator result used in the example.

Forever Forward Incremental

If you select Forever Forward Incremental, the calculator does not create periodic weekly Full backups.

The model includes:

1 × Full
+
increments resulting from retention
+
Working space

For an official Backup Copy Job without GFS, Veeam uses forever forward incremental for short-term retention.

How does the calculator size Veeam Cloud Connect Hardened?

For Hardened, we assume a weekly chain:

1 × Full
+
6 × Incremental

Retention cannot effectively end before the immutability period:

effective period =
max(retention, immutability)

Retention and immutability are not added together.

The number of chains required by the effective period is:

ceil(effective period / 7)

In addition, there is always one current chain:

Full + 6 × Incremental

and:

Working space =
1 × Full + 1 × Incremental

For example:

Retention:       14 days
Immutability:    14 days

we get:

2 chains resulting from retention/immutability
+
1 current chain
=
3 chains

that is:

3 × Full
18 × Incremental
+
Working space

For 10 TB of data, 50% reduction, and 5% DCR, this gives:

15.00 TB Full
 4.50 TB Incremental
 5.25 TB Working space
----------------------
24.75 TB

Important for Hardened

Immutability may keep a backup protected longer than the job retention itself.

If retention is 7 days and immutability is 21 days, sizing is calculated from 21 days, not 7 + 21.

Cloud4You OCS — how does Block Generation work?

Cloud4You OCS is object storage compatible with the S3 API.

Veeam uses Block Generation, which groups blocks written within a specific time interval and assigns them a common immutability expiration time.

For S3-compatible repositories, the default Block Generation value is:

10 days

If this value has not been deliberately changed in the Veeam environment, leave 10 days in the calculator.

Block Generation can be changed

Block Generation is not a regular repository parameter configured in the standard wizard.

Veeam applies the value automatically, but the predefined period can be changed using a Veeam registry setting. Veeam recommends contacting Support to determine the appropriate procedure.

If your environment uses a custom value, enter exactly the same value in the calculator.

Why does Block Generation increase required capacity?

Example:

Job retention:          30 days
Minimum immutability:   14 days
Block Generation:       10 days

When protection applies for the entire retention period:

max(30, 14) + 10
= 40 days

The calculator therefore assumes at least:

40 days of data

for sizing, not only 30 days.

If Block Generation is increased, for example to:

30 days

the same example gives:

max(30, 14) + 30
= 60 days

and the calculator includes 60 days.

Protection for the entire retention period

For the Veeam option:

For the entire duration of their retention policy

we calculate:

protection period =
max(job retention, minimum immutability)
+ Block Generation

Minimum immutability period only

For:

For the minimum immutability period only

Veeam ignores the job retention when calculating the immutability period itself:

object protection period =
minimum immutability
+ Block Generation

For Cloud4You capacity, the calculator still uses the larger value:

modeled capacity period =
max(job retention, object protection period)

This prevents the calculator from underestimating required space when job retention is longer than the immutability period.

Conservative OCS capacity model

Direct backup to Object Storage uses the forever forward incremental mechanism by default in Veeam.

However, Object Storage should not be sized exactly like a traditional file repository.

Veeam may extend the immutability of blocks shared by active and inactive parts of the chain. Therefore, actual storage usage may be higher than the simple result of:

Full + Daily Change Rate × retention

For this reason, the Cloud4You calculator uses a conservative model:

1 × Full after reduction
+
Daily Change Rate after reduction × full modeled capacity period
+
OCS safety margin

We deliberately calculate daily changes for the entire modeled capacity period instead of subtracting the first day.

The default OCS safety margin is:

20%

It can be changed, but when planning a new service we do not recommend reducing it before observing actual repository usage.

Do not purchase capacity exactly equal to the calculated result without a margin

Daily Change Rate is an average value, and Object Storage usage may grow in steps.

For a new service, we recommend retaining a safety margin. If the environment has a high or unstable Daily Change Rate, consider increasing it above 20%.

GFS and manual Full backups

If the environment uses:

  • GFS,
  • periodic Active Full backups,
  • manually triggered Active Full backups,
  • non-standard schedules,
  • multiple jobs writing to the same quota,

the result of the basic calculator may be insufficient.

Veeam also applies Block Generation to GFS backups and may extend the protection period of blocks.

In such a scenario, sizing should be verified individually before purchasing capacity.

Veeam sources

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