1. How can you verify data immediately after backup?
Is there a ready-made solution for checking data integrity?
2. Type of backup “User Archive” whether it takes precedence over “User Backup” in terms of the reliability of the backup.
For example, an improved validation algorithm ...?
What do you mean "Verify data immediately after backup" ?
If you want to compare the backed up data with the data on the disk, no you can not do that. I can not recall a backup software that will do that.
Netbackup can read the backup, compare the files with its database and guarantee that the expected files are in place and readable.
This can be done using the verify option in the GUI -> catalog or with the bpverify command. You can create a script that runs the bpverify command after the backup.
user archive and user backup are the same. But user archive deletes the files after a successful backup.
Verifications of backup is something that belongs to the past, where tape drive was unreliable. Today all moderne tape drives does automatic read after write to ensure data is correctly written.
Also a 1:1 compare is impossible, because no file system today is static, changes are written constant.
If integrigity if of your concern, perform restore test either bi-weekly or on a monthly basis.
Backup vs archive: The method to store data is the same, so reliability is the same, else what Stefanos said.
crc32 sum for all the files
Backup the files
Restore files to alternate location - perform CRC32 check again, and compare with result form first CRC32 run
Duplicate backup to second tape. Store the tape in different location.