calculating backup size

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calculating backup size

Veeam Logoby janpaulsmit » Thu Oct 03, 2013 7:04 am

We use Veeam 7, and thanks to the new backup copy job feature we can use GFS-rotation, but I'm wondering how many full backups the backup copy job will create in the folowing situation:

Backup scheme:
* every 2 hours: 12 restore points
Backup copy:
* once a day: 14 restore points
* Weekly: 4 restore points
* monthly: 12 restore points
* yearly: 5 restore points

How many full backups wil I have? It's important to know to calculate the required disk space by using this formula:

Backup size = C * (F*Data + R*D*Data)
Data = sum of processed VMs size (actually used, not provisioned)
C = average compression/dedupe ratio (depends on too many factors, compression and dedupe can be very high, but we use 50% – worst case)
F = number of full backups in retention policy (1, unless backup mode with periodic fulls is used)
R = number of rollbacks (or increments) according to retention policy (14 by default)
D = average amount of VM disk changes between cycles in percent

Data=11TB and will grow to 22TB in 3 years

Thanks!
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Re: calculating backup size

Veeam Logoby Gostev » Thu Oct 03, 2013 7:20 am

1 + 4 +12 + 5 = 20 full backups in 5 years.
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Re: calculating backup size

Veeam Logoby janpaulsmit » Thu Oct 03, 2013 7:53 am

Thank you for your quick reply!

Just to summarize and to be sure, I put down the following calculation based on 11TB VM-size, 50% dedup/compression and 5% change rate

'Normal' backup:
Backup size = C * (F*Data + R*D*Data) (every 2 hours 12 restore points)
Backup size = 50 * (11*5 + 12*1*5)= 8,8TB (approximately)

backup copy:
Backup size = C * (F*Data + R*D*Data) (1 daily with 14 restore points, 4 week, 12 months, 5 years= (1+4+12+5) 22 full backups)
Backup size = 50 * (11*5 + 14*22*5)= 124TB (approximately)

Do you think this is a realistic calculation?
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Re: calculating backup size

Veeam Logoby foggy » Thu Oct 03, 2013 9:18 am

Jan, before answering your question, could you please clarify the following:
- What is the backup mode for the normal job? Forward or reversed incremental?
- What is the expected average amount of VM disk changes between cycles in percent (D=?) If I can derive it correctly from the 3 year 22TB estimation, it is ~1%, is that correct?
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Re: calculating backup size

Veeam Logoby janpaulsmit » Thu Oct 03, 2013 9:29 am

The backup mode is reversed incremental.
The customer gave us these figures: 11TB diskspace use now and expected grow to 22TB in three years. So the 1% would be correct.
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Re: calculating backup size

Veeam Logoby foggy » Thu Oct 03, 2013 9:47 am 1 person likes this post

Well, since this formula reflects the amount of space required at the specific moment in time (and does not reflect the fact that the size of the full backup (Data) increases with time), you could calculate the maximum space required after 5 years of running both jobs and it will be something like that (actual space will be less):

janpaulsmit wrote:'Normal' backup:
Backup size = C * (F*Data + R*D*Data) (every 2 hours 12 restore points)
Backup size = 50 * (11*5 + 12*1*5)= 8,8TB (approximately)

50%(1*22+12*1%*22)=12.3TB

janpaulsmit wrote:backup copy:
Backup size = C * (F*Data + R*D*Data) (1 daily with 14 restore points, 4 week, 12 months, 5 years= (1+4+12+5) 22 full backups)
Backup size = 50 * (11*5 + 14*22*5)= 124TB (approximately)

50%(22*22+14*1%*22)=243.5TB
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Re: calculating backup size

Veeam Logoby AdrianHinton » Fri May 30, 2014 9:37 pm

Hi, Can I please jump onto this one and as the same question but only about the copy job and with no Deduplication on the target?

VM Current Size = 995GB

Backup Job size 1.4TB
Backup is Incremental
Backup Job Retention
Restore Points to keep = 91

Copy Job Retention
Restore Points to keep = 91
Weekly Backups = 3
Monthly Backkups = 11
Quarterly = 0
Yearly = 1

Thank you!
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Re: calculating backup size

Veeam Logoby foggy » Mon Jun 02, 2014 1:08 pm

Adrian, I need to ask a few clarifying questions:

- do you need to calculate the amount of space required for both normal and backup copy jobs?
- what is the average amount of changes inside you VMs in percent?
- is periodic synthetic or active full scheduled for the normal backup job?
- what is the "Copy every" interval for the backup copy job?
- what do you mean by "no deduplication on target"? Do you mean raw storage on backup repository or you're saying Veeam dedupe is disabled for the backup copy job?

Thanks.
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[MERGED] Definitive method(s) to calculate storage requireme

Veeam Logoby AdrianHinton » Mon Jul 21, 2014 11:11 pm

Hi,

I have been searching for the definitive way to calculate how much storage I need for backup copies. I can't seem to find anything truly useful and I am surprised that I can't, especially considering how widely used this product is. All of the forum posts that I have read seem only intelligible to those who have asked their specific questions based on their specific configurations. Is there a utility out there that one can use to determine how much space would be required over time in a backup-copy repo? What is the formula for any given scenario?

I have a VM, VeeamOne reports the change rate, VMWare tells me the VM size, I get to decide how many RP's I want to keep, the type of backup it will be and the archival retention. The disk in the repo is either Windows dedup enabled or not; How do I put all that together to know how much storage I will need available for 12 months, 24 months, 36 and so on?

I would really like to write a program so I can input a few values in and it can calculate or estimate these storage requirements for me. I would have though Veeam have already done that but my searches are proving useless in this area.

Looking forward to hearing from you and thank you for your support!
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Re: calculating backup size

Veeam Logoby foggy » Tue Jul 22, 2014 6:56 am

Adrian, there's no such a tool, however knowing the values you're talking about, you could perform a rough estimate of the space required using the formula and examples given above.

Hope this helps.
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Re: calculating backup size

Veeam Logoby AdrianHinton » Mon Jul 28, 2014 10:44 pm

Hi and thank you for the reply. Could you help me understand the formula with the below values?

VMSizeGB = 1007.51GB
AVGChangeRateGBPerDay = 166.43GB (Reported by VeeamOne against the BackupJob)
BackupType = Incremental
RP's to keep = 7
Weekly = 3
Monthly = 11
Quarterly = 0
Yearly = 1
TargetDisk Dedup savings = 50%

Thank you!
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Re: calculating backup size

Veeam Logoby dellock6 » Tue Jul 29, 2014 7:56 am

Adrian,
based on the rule of thumb of 50% reduction (conservative assumption to keep you on the safe side), you will have:
Full backup 500Gb
Incremental backup 83 Gb

So, with a 7 days incremental backup you will end up in reality to have 2 weeks of backup files, made of 2 fulls and 12 incremental. This means the storage usage will be 2 Tb of space for regular retention.

For GFS retention this is more simple, you simply count 500Gb and multiply it for the number of restore points, since all of them are fulls. So, again in your case it will be 15 restore points, that is 7,5 TB for GFS.

Luca.
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Re: calculating backup size

Veeam Logoby AdrianHinton » Thu Aug 07, 2014 4:11 am

dellock6 wrote:Adrian,
For GFS retention this is more simple, you simply count 500Gb and multiply it for the number of restore points, since all of them are fulls. So, again in your case it will be 15 restore points, that is 7,5 TB for GFS.


If I look at my repo for a particular job and see a size for my latest VBK, I can add up the restore points to keep, multiply by the size of the latest VBK and that will give me my GFS storage requirements?

Latest VBK for a job = 365GB
GFS
Weekly = 3
Monthly = 11
Yearly = 1
Total = 15

Does it follow that for a year the GFS retention will equal 3+11+1*365GB/1024=5.34TB? And double that for 2 years?

If so, how does Server2012 dedup come into play when we are planning the physical storage for this? Will that yearly 5.34TB be deduped 50% (conservative estimate) and require that I have a minimum of 2.67TB of storage for a year just for GFS? Or will dedup do a better job on all these vbk's because they contain similar data?

I'm really confused as to how a company plans for VB&R storage. And surprised there is not a utility to calculate the requirements based on the way one wants to backup and archive.
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Re: calculating backup size

Veeam Logoby dellock6 » Thu Aug 07, 2014 8:11 am

No double, on a 2 year base you will only add an additional yearly restore. Monthly 11 for example means keeping last 11 monthly restore points, no matter if you then go for multiple years. So the count will be 3+11+2=16.
Also, consider some additional space due to the fact your infrastructure will grow during time, and 1 year from now your VBK could be bigger in size.
Finally, windows dedupe will probably go well beyond 50%, considering as you correctly guessed the content of VBK files is similar, but the actual results could vary. You can look in other threads in these forums where other users have posted their results.
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Re: calculating backup size

Veeam Logoby foggy » Mon Oct 20, 2014 1:17 pm

For those who are interested in assessing disk space required for backup repository, here's a handy calculator based on the formula above (created by Timothy, one of our systems engineers).
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