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Backup Strategy

Hi I am trying to figure out my best bet backup strategy. I know in an ideal world its best to just go with full backups every night but what if space it tight. So im also looking at differential and incremental as well. Although its hard to tell really what data will change on a daily basis my question is what would the diff and incremental space requirements look like if the fist complete backup was say 10GB to keep it simple then then next night 5GB of data had changed the night after that 30GB had changed and so. if there a model i could follow to see what size and how many tapes i might end up needing.

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Lee W, MVPTechnology and Business Process AdvisorCommented:
Wow... you're using tape and not cheaper external hard drives?  Are you virtualizing so you can create off-site replicas?

As for backup space, a differential backs up everything that has changed since the last full backup., even stuff backed up in last night's differential.

An incremental backups up everything that has changed since last nights incremental.

Differential/Full is one of the easiest to restore - you restore you last full and your last differential and you're back to where you were.

Incremental/Full keeps each nightly backup short and relatively small (as small as it can be) but restores are pains because now you have to restore your last full and EVERY subsequent incremental since the last full.

I'd suggest you start analyzing your data usage on the server to get a good idea of what you need.  Make some excel spreadsheets...
Found those files online, give them a try
You can do daily backups on hard drives, weekly, monthly, quarterly, etc on tapes.
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kingcastleAuthor Commented:
good idea on the excel and yes we looking at tapes and cheap HDD but budget will decide i guess.

on the spread sheet if we model the 3 types on a typical few days of data for example
mon 10GB
Tues 25GB
Wed 5GB

to start me off what would that look like?
A full backup on monday would take 10 gb, just add other days per your estimate. Best setup a test backup job US ng lat cal or network hdd, check the size.
kingcastleAuthor Commented:
Ok so what would the diff and incremental look like if the full is just adding to my example above?
If the backups were 10,2,2,2,2,2,5gb you would need at least 25gb or 30 gb on tape.
kingcastleAuthor Commented:
So on the Incremental backup for example if my initial first full backup was 10gb but the the next day 25gb of data was created does this mean I add 10gb and 25 gb together to get total storage requirement for that incremental backup?

If so how does that differ from full backup because wouldn't I be backing up 10gb first day and if 25gb was added the second day I would still be backing up 35gb in total same as incremental so how does incremental save space?

If your data is 10 GB:
Monday: full backup 10GB
Tuesday: files changed since Monday: 1GB
Wednesday: Files changed since Tuesday: 2GB
Thursday: Files changes since Wednesday: 1GB
Total: 10+1+2+1=14GB + small overhead.

Full backup Mon-Thu would be 10 x 4 = 40GB
Gerald ConnollyCommented:
Or you could go Full backup tonight and then do "incrementals forever" with Synthetic Fulls on a daily/weekly/monthly cycle.

There is nothing wrong with using tape, it definitely has the potential for long term archival storage - role it was designed for (unlike removeable disks) .

Backing up to disk is probably slower than backing up to Tape, but its saving grace is its restore speed.
kingcastleAuthor Commented:
So basically is the difference between a full backup schedule and a differential backup schedule really just the original size of te first full backup?

So for example if I has mon, tues, we'd, thur on a full of 10gb, 10gb, 10gb and 10gb total 40gb
And on the same for diff total would be 30gb basically tues, we'd, thurs
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