What is the best way to make an offsite backup?

[Daniel_Krugjohn]

This is what I want to do,

1. Every Friday make two full backups (one backup to keep onsite and one to take offsite)

2. The rest of the week create differential backups

This is my concern; if I simply run the full backup job twice on Friday then the first run will reset the archive bit on all files. After the first run files may change and then the second run will reset the archive bit on all files. Then the next differential backup will search for files that have changed based on the archive bit. There is now a possibility that files which changed since the first full backup will not be included in the next differential backup (because there archive bit was reset by the second backup).

After reading around on the newsgroups and the manual, it looks like the best way to handle this is to backup up to disk and then create two tape duplicates from that disk backup. As I understand it there is no way to create a duplicate backup off of an existing tape to another tape if you have only one drive. Is this correct?

Any input, clever ideas, personal experience with the matter would be greatly appreciated. Thank you.

[William_Geater]

Someone will correct me if I am wrong, but you should be able to do a "copy" on one of your full backups, which will not reset the archive attribute.

[Russ_Perry]

You pretty much answer your own question but I'll restate the options...You can either run 2 full backups which might differ slightly based on what data is present to be backed up. A full backup will back up all files present whether the archive bit is set or not but the second full will possibly be different from the first. Restoring from a later differential will require the latter full backup and latest diff to bring the data back to the last diff backup. The other option if you want the same data in both backups is to run a duplicate job of your first full backup. As you mention, this will require either 2 tape devices or will require running the initial full backup to disk then the duplicate to tape.

[Daniel_Krugjohn]

Thank you for the reply William. Yes, I believe you are correct. As I stated in my second to last paragraph I think this is the solution to the problem. I was looking for confirmation on this method or a "better" or another way to do this task. I was also curious as to whether or not you could create a duplicate tape backup with only one tape drive.

[Daniel_Krugjohn]

> As you mention, this will require
> either 2 tape devices or will require running the
> initial full backup to disk then the duplicate to
> tape.

Thanks for the reply Russ,

I'll go ahead and assume that this is the correct method for creating an offsite backup.