Backup Types

Daniel333

Does anybody have an easy way to memorize backup types, and how they work? I keep getting killed on questions like,

"On May 1, you ran a full backup. Last Friday, you ran a differential backup. On Monday, Tuesday, and Wednesday, you ran incremental backups. You server dies on Thursday. With which backup do you begin your restoration?"

bighornsheep

Incremental and Differential will both preform backup on files with the archive bit on. But incremental will turn off the archive bit after it finishes the backup. Where as differential will leave the archive bit as is.

Daniel333

So differential would keep backing up the same information over and over again, while incremental would not recopy the same information?

For example, you do a full backup. Then differential, then differential again. You would have to only restore the full backup and then the last differential?

bighornsheep

deshana wrote:

So differential would keep backing up the same information over and over again, while incremental would not recopy the same information?

For example, you do a full backup. Then differential, then differential again. You would have to only restore the full backup and then the last differential?

Differential & Incremental backs-up data that has the archive bit set/on
The difference is that Incremental will turn off the bit after it finishes.

Copy and Full backs-up data regardless of the archive bit, the difference again is that Full-backup will turn off the bit after it finishes.

In other words, if you do full back-up, differential, differential again with no data changes, the 1st differential and the 2nd is the same.

Daniel333

thanks man, think I got it now. On to the next problem!

bighornsheep

No problem. It's what this board is for.
Let me know if you have other questions, I'll try and help you out.

Daniel333

haha, yeah. I will!

*opens pandora's box*

TheShadow

Just in case you are wondering why it is done that way. Incremental saves on the amount of backup media and time needed as only those files changed since any backup has been done are collected. Differential saves restore procedure time at the expense of more backup media and backup time since, only two backup sets are needed for a restore; i.e. the original full backup and the very last differential backup. Incremental would have needed the original and ALL incremental backups to do a complete restore. Daily incrementals also have the advantage of restore speed if you just wanted to recover yesterdays changes.

jojopramos

If you are only have a smal datas to backup, rather do the Full Backup then Differential Backup.....But for Large datas, It's Full Backup and Incremental....just make sure you are verifying and test/restore it once/twice a week to make sure that you're backup is really working well or else???

phaser

deshana wrote:

Does anybody have an easy way to memorize backup types, and how they work? I keep getting killed on questions like,

"On May 1, you ran a full backup. Last Friday, you ran a differential backup. On Monday, Tuesday, and Wednesday, you ran incremental backups. You server dies on Thursday. With which backup do you begin your restoration?"

Please shed some light here ... but is this the type question one would really get on a test? I only ask because I thought it was "taboo" to mix incremental & differential backups.

Or, is this something asked to check your "concept/theory?" knowledge .. not something you would necessarily do?

I think I asked that properly.