Why (why not archive bit) use Modified Time on windows servers?!

[atos]

if you only backup windows servers, is there any reason to use Modified Time?

why shouldnt you use Archive Bit?

the reason i ask is that since we changed to Modified time we hav had some problem with that the Differential backups backs upp ALL data, not only the changed data. i read soewhere that if the last backup "failed" it will backup all data again, and by failed i mean skipt some files and could not find files that had been moved.

and one more thing, if i change all backups from modified time to archive bit, will the first backup after the change do a Full backup av all files because the change of backup method? or will it do Differential backups as it says in the backup policy?

regards

Johan

[Ken_Putnam]

if i change all backups from modified time to archive bit, will the first backup after the change do a Full backup av all files because the change of backup method?

Almost certainly

As to differences bewteen modified time and archive bit

The Full - Using modified time backup method adds the time of the backup to the Backup Exec database only if the full backup job completes successfully. If the full backup job does not complete successfully, any subsequent backup jobs that use the differential or incremental modified time backup methods back up all of the data instead of just the data that changed since the last full backup.

From

http://www.symantec.com/docs/HOWTO22704

[Kiran_Bandi]

just for your information atos.

Unless you choose BE too use backup methods depnds on modified time, BE uses the archive bit to determine whether a file has been backed up or not.

Regards...

[atos]

ok, thx for answering!

But is there any advantages or disadvantages when using modified time or if you use archive bit?

lite speed loss, one is more reliabale etc?

//Johan

[pkh · Accepted solution]

One advantage of using modified time in Windows system is that BE uses the USN journals when comparing timestamps of the files to determine which file to backup.  This is a much quicker process than checking the archive bits of individual files.  The later method means that you have to examine each file in the selection list which can be a lengthy process if you are backing up a lot of files.

Some anti-virus software will cause a differential backup using modified time to become full backups.  See my blog below

https://www-secure.symantec.com/connect/blogs/incr...

If you are not using SEP, you should check with your AV vendor to see if they are aware of a similar problem with their product.

When you switch backup methods, i.e. from archive bits to modified time or vice-versa, you should always do a full backup to establish a baseline.