We are going to upgrade from fedora 6 to fedora 8.
Can we use the /backup directory to restore whm/cpanel on fedora 8 and ensure that all the cpanel users/sql is intact?

Thank you for you help

In short: Yes.

Long: You may want to check carefully after reinstalling. We had cases where cpanel randomly dropped tables out of databases and other very strange issues with the backups.

Thanks for your answer. I just found out Fedora 8 doesn't work with CPanel so it's either Fedora 7 or CentOS.
Is it possible to use the backup on a different OS then it was made from?

Is it possible to use the backup on a different OS then it was made from?

I think so. The difference between Fedora/RedHat/Centos is rather small, you shouldn't see any problems.

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Is it possible to use the backup on a different OS then it was made from?

Yes, especially if you're just moving from one Linux distro to another. However I've even seen people take cPanel backups from Linux and restore them to FreeBSD and vice-versa with minimal issues.