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NFS V4 file backed up after file system unmounted and mounted again.

Technote (troubleshooting)


Problem(Abstract)

A Tivoli Storage Manager Backup-Archive client is used to backup files located on an NFSV4 mount point on Linux. The NFSV4 file system is unmounted. After the NFSV4 is mounted again, the files are backed up again although they have not changed.

Cause

The Tivoli Storage Manager Backup-Archive client for Linux does not support NFSV4 ACL.

Diagnosing the problem

To determine what causes the fiole to be backed up again, it is necessary to capture a trace of the

incremental back of the NFS mount point. Use the following command :

dsmc i <nfs_mount> -tracefile=tsmtrace.txt -traceflags=fioattribs

Replace "<nfs_mount>" with the actual NFS mount point path. The trace will be written to the tsmtrace.txt file in the current directory. Examine the trace to determine what caused the file to be backed up. For example :


11/18/2013 11:20:11.250 : incrdrv.cpp         (10993): Incremental attrib compare for: /mynfs/myfile.txt
11/18/2013 11:20:11.250 : unxfilio.cpp        (1865): fioCmpAttribs: skipACL:'0', skipACLUpdateCheck:'0'
11/18/2013 11:20:11.250 : unxfilio.cpp        (2006): fioCmpAttribs: Attribute comparison of two files
Attribute       Old       New
---------       ---       ---
fsType         2         2
ctime 1385188691 1385188691
mtime 1385188691 1385188691
atime 1385274170 1385666360
File mode OCT    100644    100644
uid         0         0
gid        96        96
size 326396145 326396145
ACL size         0         0
ACL checksum         0         0
Xattr size       188       188
Xattr checksum 1507905696 3537319871
inode     30871     30871
11/18/2013 11:20:11.250 : fileio.cpp          (3579): fioCmpAttribs(): old attrib's data from build (IBM TSM 6.4.1.0)
11/18/2013 11:20:11.250 : unxfilio.cpp        (2102): -->XATTR different: returning ATTRIBS_BACKUP

In this example, the "Xattr checksum" attribute changed, causing the "/mynfs/myfile.txt" file to be backed up again.


Resolving the problem

The Tivoli Storage Manager Backup-Archive client for Linux does not support NFSV4 ACL. Refer to the "File system and ACL support" section of our online Information Center for more information on what is supported.


Since NFSV4 ACL is not supported with the Linux client, on of the following two options may be used :

1) Use NFSV3 for the mount point

--OR--

2) Use NFSV4 for the mount point and also use the following option with the client backup :

SKIPACLUPdatecheck YES

With this option, the client will not perform the ACL checksum and size comparison and so, even if the ACL checksum changes (as indicated in the above example), the file will not be backed up again.

Document information

More support for: Tivoli Storage Manager
Client

Software version: All Supported Versions

Operating system(s): Linux

Reference #: 1657636

Modified date: 21 September 2017


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