NDMP - Reason for preliminary file scan?

[systematic92]

Hi Guys,

When we do NDMP backups, I believe BEXEC does a preliminary file scan of the directory we are backing up. I believe this read operationtakes place before the write operation. What option in BEXECs job settings does this and can it be disabled?

The reason I ask is because we have a very large folder full of millions of files. And the file scan process is taking up to 4 days to complete! I believe there are two options in BEXECs NDMP setting:

- Enable File History

- Backup Access Control Lists

I understand the first option when unchecked will prevent us from doing single file restores???? Example:

Folder A has files doc1 and doc2 in them. If file history is enabled, we can restore doc1 or doc2. If file history is not enabled, we can only restore Folder A and not select at a more granular level?

Is that correct?

The second option of backing up access control lists seems self explanatory however, I question if this in fact needs to be enabled. Example:

doc1 originally resides in FolderA and has read-only perms for the Finance Department.

If access control lists option was enabled, then doc1 would retain the read-only perms for the finance department if restored. If access control lists option was disabled, the doc1 would be restored without any security permissions. I am assuiming that if the latter was true, the ACLs would immediately propagate once the file was placed in its original location on the network (via inherited permissions etc.)

Is my understanding correct?

I would be grateful for an answer but most importantly I would really like to stop the read only operation of file scanning before writing. it is killing us.

Thanks,

[RahulG]

Check this if it applies.

Go to Tools ---> Options ---> Preferences and enable Display progress indicators for backup jobs. This  requires additional time to pre-scan devices.

For your question refer http://www.symantec.com/business/support/index?page=content&id=HOWTO23316&profileURL=https%3A%2F%2Fsymaccount-profile.symantec.com%2FSSO%2Findex.jsp%3FssoID%3D141800200986010aI4t19SJENh6Y7RnuEM8v9t5RqT7K21sruB

[Gurvinder]

http://www.symantec.com/docs/TECH139630 The Pre-Scan option is not supported for NDMP filer backups since BE 2010 R3. Since we do not have an agent it will not work and should be deselected.

Since there are lot of files you can uncheck the enable file history option and check if that improves the backup job rate. The downside it that if you need to restore you will have to restore the entire volume and individual files cannot be restored.

Your understanding about backup ACL and enable file history is correct.

[systematic92]

Hi Gurvinder,

Thank you for your response.

I need to be clear - I am not talking about the PRE-SCAN (green progress bar), I am talking about the backup behaviour of when we back up file off the SAN. The backup does not start immediately as it does some sort of initial read operation scan and this part is taking a long time given that we have many many files in the directory.

I think you are correct in saying that the reason for this is due to the "enable file history" but we regularly find users requesting a single file restore so I am not sure if the option of deselcting it is possible.

What would happen if I disable ACL? Would that speed up the READ operation on backups?