Backup Repository Storage Calculation

[buzzzo]

Hi

I'm a newbie so please forgive me my lack of knowledge about the product.

I need to migrate from a traditional (physical) backup solution (backupexec to tape) to veam.
The actual backup policy is:

a) 1 FULL on saturday
b) 5 differential from monday to friday
c) 1 monthly FULL

In this way i retain:

a) last 5 incremental
b) last weekly full
c) 12 Monthly FULL

In order to switch to veam i need to ensure that i could implement the same policy.
Data to backup size is about 600 gbs.

What'is the logic behind storage calculation ?

Thx in advance

[foggy]

The actual size of the storage required to implement any backup strategy depends on too many factors to be predictable. For example, without knowing the amount of changes occurred inside VM guest OS between job cycles it is simply impossible to estimate the space to store backups. There are also other factors. So only tests are able to give you the real numbers here. Probably, this thread will be useful for making some assumptions.

[buzzzo]

Hi Foggy

Thx for reply

I need to make a raw estimation and, based on that, I will size the hardware.
So test is a time consuming job that can't be made in a startup phase.

I've already read this thread by I can't figure out exactly the size.
I can't assume that:

1) compression should be at least 50%
2) data's change is 10%
3) Forward incremental is used

So could you please kindly help me after I outlined there Info ?

Thx again

[foggy]

Ok, provided that the forward incremental job will be set to keep 6 restore points at any given moment in time, you will need space for 2 fulls and 10 increments just to be able to retain a) last 5 incremental and b) last weekly full. According to the formula mentioned in the referred thread and data provided above, the rough estimate will result in 50% * (2 * 600GB + 10 * 10% * 600GB) = 900GB. Note that this is just the space required for this job in the beginning of its operation and will grow with time.

Plus space for 12 (or 13, if you are going to use backup copy job to create them) monthlies, whatever size they will be, starting from ~300GB for the very first one.

[buzzzo]

Thx very much Foggy.

And with reverse ? how much space does it use ?

Thx again

[foggy]

With reversed incremental you need space exactly for the required number of fulls and incrementals (i.e. 1 full and 5 incrementals in your case).

[buzzzo]

Thx Foggy

And I could i manage the retention with reverse ?

[foggy]

Sure, you can specify the required number of restore points to keep for any backup mode, either forward or reversed incremental.

[buzzzo]

Hi Foggy

You have said "With reversed incremental you need space exactly for the required number of fulls and incrementals (i.e. 1 full and 5 incrementals in your case)."
But in total with reverse how much space do i need to mantain the sample retention period:

a) 1 FULL on saturday
b) 5 differential from monday to friday
c) 1 monthly FULL

Thx in advance

[foggy]

How are you going to set up monthly fulls? Second backup job with a separate monthly schedule or backup copy job with GFS?

[buzzzo]

Hi Foggy

Dunno the difference between the two options.
Which one is the best ?

Thx

[foggy]

Second backup job will pull the data from the production storage creating active full each month, while backup copy job synthetically creates restore points in target location from the changed blocks extracted from the source backup storage and its activity is performed outside the backup window, without affecting production VMs at all. What best suits your requirements is completely up to you.

That said, as I already stated above, the math is pretty simple with any approach: if the goal is to keep another full backup each month, you can take the space required for the year's worth of monthlies as roughly 12*(size of the full backup), keeping in mind the data growth.

[buzzzo]

Thx foggy

Ok so, to end the thread, the sum of space required for each of the two approach (forward incremental vs reverse one).

600 gb full, 300 gb inc

FORWARD: (2 * 600GB + 10 * 10% * 600GB) = 900GB + 13 * 300 = 4.8 tb
REVERSE: 12*600= 7.2 tb

Seems that in term of space forward is much better than reverse then.

[foggy]

While your calculations for forward incremental mode are correct, I'm not sure I understand those for reversed mode. For me it will be like the following:

50% * (1 * 600GB + 5 * 10% * 600GB) = 450GB + 13 * 300 = 4.35TB

[MadAsToast]

Hi,

hoping you might be able to help, we are buying some new disks for our DR site, we are intending on rolling Veeam version 7 onto a new set of disks, is there a recommended method of identifying what total capacity is needed assuming we keep 5 rollback points.

I assume there's a formula that can be applied to "roughtimate" whats needed?

Thanks in advance

Chris

[foggy]

Chris, you could perform a rough estimate of the space required using the examples outlined above. Thanks.