Ntbackup Incrementals

A client has two external USB hard drives which are being used to store backups. The idea is to have hard drive 1 perform incrementals on a Mon, Tue, Wed and Thur, it will then do a Full backup on a Friday and then be replaced with the second drive which will follow the same pattern, being replaced after Friday's full backup with drive 1 and starting the cycle again.

We've got the Friday night full backups in place, but I'm not sure about the incrementals. Using ntbackup, do I need to have 4 backup jobs for Mon, Tues, Wed and Thur so that the files rotate, or can I simply have one file and replace it? What I'm confused about is what is backed up in an incremental, everything modified since the last full backup or everything modified since the last incremental. If it's the latter, then obviously I will need 4 jobs, if it is backing up everything since the last full backup then I can have just 1 job which will replace the file from the previous evening.

I know rotating drives on a weekly basis isn't a brilliant method, but the client won't be looking into daily rotation and tape drives imminently. (They have a rather small network at present, and actually data wise they save and modify very few files)

Thanks, tigermatt
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tigermattAsked:
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-DJL-Connect With a Mentor Commented:
Incremental back copys everthing that changed since the last incremental backup.  That means when you restore you have to do the full backup and then each incremental back since that full backup.

You will need a job for a each nights backup.  You could use one, and just get NTbackup to append the data to the file, however the file will continue to grow week on week unless you delete it regularly.

You say they don't change much data.  The best solution would probably be to do a nightly differential backup instead of the incrementals.  Differential backups copy everything thats changed since the last full backup.  Use the same job for each differential backup, and make sure NTbackup overwrites the previous nights differential backup.

Then make sure Volume Shadow copy is active so if they accidentally delete files or change something accidentally they can recover it using Shadow copies rather than going to the backups.

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tigermattAuthor Commented:
It sounds like a differential is the type of backup I'm looking for, at the moment anyway. Have you got any references to confirm what you have mentioned regarding the behaviour of the differential backups?

Thanks
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tigermattAuthor Commented:
That's perfect, now that I've seen it in 3 different places I'm quite happy that the differential will do what I want and think it will do. As you can imagine, I don't want the backups to go wrong!

One last question: When I created the backup jobs for the full backups, I copied the BKS file to a folder on the local hard drive. As far as I'm aware, the BKS only contains information regarding the data to back up, so could I use the same BKS for both the full and differential jobs, and just change the parameters on the command line so that it is running a differential backup (i.e. change /m normal to /m differential)?

Thanks
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-DJL-Commented:
Yes you can use the same *.bks

Make sure that the backup account has access to the folder where the *.bks file is located.

Out of intrest how are you handling the ejection of the USB hard drives?  Manual user ejection?
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tigermattAuthor Commented:
Thanks, the service account which the backup is running under has Administrator/Domain Admin rights, so will definitely have permissions over the BKS file.

I have set the USB drives so that they are optimised for quick removal, and we are only changing the drives once a week at present. The differentials will be run Mon, Tues, Weds and Thurs, followed by a full over the weekend and thendrive change on Monday. I thought enabling the quick removal optimisation would mean I don't have to safely remove the USB drives, although feel free to add your own comments. If necessary, I guess I could write a batch file to do the full backup which could run a command to do the safely remove on the drive after the friday night full, ready to be disconnected the following Monday?

-tigermatt
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-DJL-Commented:
No that should be fine.  Worthing doing a test though as I know some drives are picky about it.

If you need to you can use devcon to remove a device.
http://support.microsoft.com/kb/311272
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tigermattAuthor Commented:
I think I'll write a batch file which calls devcon at the end to safely remove the drive after every full backup, I'd rather things were safe and be a little more convoluted than lose the backup data. Thanks for the link!

-tigermatt
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tigermattAuthor Commented:
Thanks so much, this is just the information I was looking for and I appreciate your quick response which has subsequently allowed me to get my backups sorted this evening. Thanks for your further assistance with my other minor questions in my comments, much appreciated! :-)
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