Backup Exec 2012, incremental and differential

[PeterGust]

Hi

I have tested the brand new BE 2012, and I discovered that I cannot do a incremental and differential backup on the same machine. Why this change?
We use INC and DIFF for all servers.

[Striker_303]

Just wanted to know why do you run full + Incre +diff for same server.

I believe in BE 2012 you can only have full + incre or full + diff stage backups

[CraigV]

...it's probably because both will clash with data being backed up due to the way both look at the data compared to the last backup.

If it was different backup jobs completely with each backing up different data, not a hassle. But it might have been done to avoid any issues running both types of job at the same time.

[Colin_Weaver]

We never recommend mixing Differential and Incrementals as it can get complicated to work out the required media for a restore. In fact in previous versions of Backup Exec we received feedback via support cases and other means that customers that mixed differentials and incrementals often needed assistance during a restore and because they then added to the confusion with mixed media retentions in some cases they could not restore as a key set had been overwritten

As such to avoid the complications and make problems like this less likely to occur mixing differentials and incrementals is not a 2012 option - it's possible this idea/descison may not be a permanent one, although it is very rare for a scenario that really needs mixed diffs and incs to be identified.

Bear in mind a number of things that used to be best practice recommendations are now fixed in 2012 this is just another one of those items.

[PeterGust]

The Backup exec PRO we hired to install and setup our Backup exec used inc, diff and full for our 120 servers.

All servers is spread out during a month, full on fridays, Diff on wednesdays, and Inc the rest of the weekdays.

What will happend when we upgrade to servers that use both inc and diff?

And when I restore, must I restore one FULL and tons of INC's.

[Ken_Putnam]

The Backup exec PRO we hired to install and setup our Backup exec used inc, diff and full for our 120 servers.

Some Pro

What will happend when we upgrade to servers that use both inc and diff?

Well, the Wed  DIFF will  not update the Archive bit, so Thurs INCR will backup all changes made Wed or Thurs  (ie you will have Wed changes twice)

And when I restore, must I restore one FULL and tons of INC's.
 

When using INCR, you must restore the last FULL and all subsequent INCR, in order

When using DIFF, you need to restore the last FULL and last DIFF

So in a mixed environement,  you would need to look at where in your backup cycle you want to restore to and decide which backups to restore 

if it was me, I'd just change the Wed DIFF to an INCR going forward

[Amarnath_Sathis]

Incremental & Differential for the same server is not needed.

Its waste of Backup Time, Backup Resources(Drives, Media's).

Full Backup + Cumulative Incremental is more effective and it also reduces the cost.

During restoration it every easy for backup admins to the till date data.

[Jason_Lee]

As a test, I did a B2D of 1.2TB of data.  VM mounted RDM's via 8Gbps fiber.  Backup storage was on seperate server again 8Gbps Fiber with a 1Gbps connection ea. between the data server, the target storage server and the BE Host.    Full backup with SW compression (78% of original) and verification took ~17.5hrs to complete.  Verification portion was roughly 4 - 5hrs of that.

Point being, doing a monthly 17.5hr backup that will only grow with time each month seems a lot.  If I can chunk this down by 1 or 2 fulls a year, monthly Diff's which would be much shorter and then dailys based on the last Diff,  well that is a much preferred method in my context.

If you need faster restore times that is what CPS was for (although it for some reason is dropped in 2012) so finding another Realtime or Near replication would be a better solution for availability of the volume as a whole, then the backups for integrity.

[RLeon]

Hi Jason Lee,

Your posts are very informative, provided very solid arguments backed by figures, and got me thinking (and calculating).

As for removing the ability to mix full, incremental and differential backups for the same server, by the same logic, one could also argue that they should also include "Towers of Hanoi" tape-backup rotation scheme feature:
http://en.wikipedia.org/wiki/Backup_rotation_scheme#Towers_of_Hanoi

This is of course not direclty related to the point you are making, and does not help at all.
This is just me giving another example of useful features not getting implemented.

RLeon

[pkh]

There are always trade-offs.  When you have elaborate backup schemes, you are trading savings in disk space and backup times with complexity during a restore.  See my article on this subject.

https://www-secure.symantec.com/connect/articles/pros-and-cons-various-backup-schemes

There is no such thing as a free lunch.

[Jason_Lee]

@pkh, agreed.  What I don't understand is the removing of the ability to create complex scenarios.  If they are concerned about "too complicated for the user" adding popup notices when non-std. scenarios are created (extremely simple, basic programming) to warn users who may not fully understand their choices that they should double-check rammifications of their config is in order, but to remove the capability (when logic was previously already available) just to 'simplify' things makes no sense.

I pay big $$ for Symantec (for our budget) specifically for my ability to be complex and sqeek out savings and customize to our specific needs... so far with 2012, not only am I losing the CPS and all the features it had which we used heavily (we've purchased CA's RHA to at least get the Near Realtime replication part back for us), but now I'm having to re-construct my whole compressed backup strategy with this removal.  Depending on needs, we will be re-evaluating maintaing BE as our program in lue of others such as CA or AppAssure.

This is most definitely a step back for BE as a product in my view (at least with my current understanding which I can very well be missing something that would negate these points, I'm just not seeing them).

[Jason_Lee]

I'm a bit confused and/or disagree.  I thought the point of a Full -> Diff -> Inc strategy is to maintain diskspace while maximizing backup windows and maintaining back-in-time

For example, do a Full backup twice a year - keep for 1year, do a monthly Diff - keep for 10months (don't do a diff on the months you do a full) and then do a daily INC - keep for 1 month.

... This would allow me to recover a given file revision any day of the current month, go back to a file as it existed at the begining of any month for the past 5 months and/or recover a file as it stood 1yr or 6months ago at the full snapshots.

The inc. would overwrite after 30days, monthlys after 6months and fulls after 1yr (or every 3rd full would be an overwrite.  You only need the storage to maintain compressed 2x's the full data's worth, your avg monthly rate of change 12x's and daily rate of change ~31x's

Backup windows would be smaller for the diffs and inc and recovery options much greater.

To do a Monthly Full and and daily Incr. yet be able to restore files under the same scenario, you would have to have 12x's the full compressed backup size and ~31x's the daily change rate and the monthly fulls would be way longer.

Given: 3TB of data, with a monthly net change of ~500GB (from the previous month) and a daily net change of ~50G (from the previous day) Full's take 6hrs, Diff's take 1.5hr and inc. take 40min on avg.  Compression avg. 80%

Full/Inc:  12*(80%*3TB)=28.8TB  +  31*(80%*50GB)=1.3TB  Total: ~30TB for backups 

                Monthly a 6hr window and daily 40min backup window needed

Full/Inc with only 2 fulls, but keep incrementals for 6months:  2*(80%*3TB=4.8TB + 183*(80%*50GB)=7.3TB   Total: 12.1TB

                Twice a year 6hr backup windows, daily 40min window needed. Still shy getting back 7-11 month ago standing.  To get that with incr, doubles that storage and requires a total of 19.4TB

Full/Diff/Inc:   2*(80%*3TB)=4.8TB  + 10*(80%*500GB)=4TB + 31*(80%*50GB)=1.3TB  Total: 10.1TB 

                Twice a year 6hr backup window, once a month 1.5hr backup window and a daily 40min backup window needed.

That's a substantial decrease in amount of storage needed and backups window time frames yet maximizing the ability to restore.

!Edited! -- in re-reading my post, I may be a little off in what exactly the proposed strategy at the top yeilds in relation to the calculations (i.e. I may be off on how many incr or diffs are kept or when they are overwritten), but they are close enough that the diff. would not change the end values much nor my point/logic, so leaving as is.