In NetBackup 6.5.6, FlashBackups taken of certain Windows mount points will not be backed up and will not be available for restore.

Article:TECH136059  |  Created: 2010-01-18  |  Updated: 2011-02-04  |  Article URL http://www.symantec.com/docs/TECH136059
Article Type
Technical Solution


Environment

Issue



In NetBackup 6.5.6, FlashBackups taken of certain Windows mount points will not be backed up and will not be available for restore.


Error





Cause



Introduction:
An issue has been discovered in NetBackup 6.5.6 affecting the processing of paths of backup directives in a FlashBackup-Windows policy which can result in failed backups OR backups which appear to succeed but contain incorrect data and are unrecoverable.  Affected paths are those which specify a particular mount point which does not correspond to a drive - for example, a mount point of \\.\E: would not be affected, but a mount point of \\.\E:\mount would be affected.  Effectively, entries are misread so that the root (drive letter) of a path is used no matter which path is specified.  Any images created which are affected by this issue are unrecoverable and cannot be used for restores.

What is Affected:
Flashbackup-Windows policies on NetBackup 6.5.6 clients are affected if they contain backup selections which do not correspond to drive letters (for example, \\.\E:\example\folder\path).

Previous versions of NetBackup are not affected.

NetBackup 7.0 is not affected.

FlashBackup for UNIX is not affected.

How to Determine if Affected:
Examine FlashBackup-Windows policy selections for entries which are not drive letters.

Additional symptoms may be displayed in NetBackup logs.  Any or all of the following may occur:

Failed backups may occur with status code 42 (network read failed) reported in the Activity Monitor.

The client's bpbkar log may indicate a failure to lock a raw device and status code 13 (file read failed):
11:48:31.817: [2228.5656] <2> tar_backup_tfi::setupFileDirectives: TAR - backup filename = BACKUP \\.\E:\Drives\Drive2\ USING \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy591\ OPTIONS:ALT_PATH_PREFIX=C:\Program Files\Veritas\NetBackup\temp\_vrts_frzn_img_6156,FITYPE=MIRROR,MNTPOINT=\\.\E:\Drives\Drive1\,FSTYPE=NTFS

11:50:40.836: [2228.5656] <2> tar_base::V_vTarMsgW: WRN - can't lock raw device for read: \\.\E: (E:) (WIN32 5: Access is denied. )

11:50:40.867: [2228.5656] <2> tar_base::V_vTarMsgW: INF - EXIT STATUS 13: file read failed

Note that in the example above, the E: drive is attempted to be locked while the expected path is E:\Drives\Drive2.  In this example, there is no intent to back up the entire drive (which has different permissions than the mount point), but that is what is attempted due to this issue.

If the backup should for some reason succeed (for instance, when there is no permission conflict between the mount point and its root drive), restore attempts will fail when attempting to navigate to the path(s) of the requested file/folder(s) for restore.  

The bpdbm log will show that an incorrect path is traversed.  In the following example, the root drive E:\ is examined when the intent is to navigate the mount point  E:\mount:
13:24:12.157 [6288] <2> image_path: ?
13:24:12.157 [6288] <2> image_dir_name: ?
13:24:12.157 [6288] <2> list_files: file list options = 0x80000402
13:24:12.157 [6288] <2> image_path: ?
13:24:12.157 [6288] <2> image_dir_name: ?
13:24:12.157 [6288] <2> index_dir: ?
13:24:12.157 [6288] <2> image_dir_name: ?
13:24:12.161 [6288] <2> strcmp_match_file_list: ?
13:24:12.161 [6288] <2> strcmp_match_file_list: pattern:/E/  level:1 path_independent:0 fl_option:0x80000402
13:24:12.163 [6288] <2> list_files: selected 2 total_selected 2
13:24:12.171 [6288] <2> process_request: request complete: exit status 0  ; query type: 79
13:25:56.472 [6378] <2> client_db: Q_CLIENT_GET
13:25:56.473 [6378] <2> process_request: request complete: exit status 0  ; query type: 223



Solution




Workarounds:
1. Configure the mount point with a drive letter and change the policy to back up that drive letter instead of the mount point.  Ensure that permissions of the root allow access.

2. Do not use FlashBackup-Windows policies to protect these mount points - instead, configure MS-Windows-NT policies with Cross Mount Points enabled.

3. Upgrade clients to NetBackup 7.0, where this issue is not present.

4.  A fix for this issue has been posted for NetBackup 6.5.6 and is available here:   http://www.symantec.com/docs/TECH152708

ETA of Fix:
The resolution to this issue (Etrack 2071154) is scheduled to be released in a future Release Update of NetBackup.

Best Practices:
Symantec strongly recommends the following best practices:
1. Always perform a full backup prior to and after any changes to your environment.
2. Always make sure that your environment is running the latest version and patch level.
3. Perform periodic "test" restores.
4. Subscribe to technical articles.

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Supplemental Materials

SourceETrack
Value2071154
Description

Individual file restores fail when the path is part of a nested mount point from Flashbackup-Windows images.


SourceError Code
Value13
Description

file read failed


SourceError Code
Value42
Description

network read failed


Legacy ID



355830


Article URL http://www.symantec.com/docs/TECH136059


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