Snapdiff

The snapdiff option is for backing up NAS/N-Series file server volumes that are CIFS attached.

The snapdiff option is for backing up NAS/N-Series file server volumes that are NFS attached.

Restriction: None of the NetApp predefined shares, including C$, works with the IBM Spectrum Protect snapshot difference option because the backup-archive client cannot determine their mount points programmatically.

You must configure a user ID and password on the backup-archive client to enable snapshot difference processing.

Use this option with an incremental backup of a NAS file server volume, instead of a simple incremental backup or an incremental backup with the snapshotroot option, whenever the NAS file server is running ONTAP 7.3.0, or later. Do not use the snapdiff and snapshotroot options together.

Restriction: Incremental backups with snapshot difference processing are only available with the Linux x86_64 backup-archive client.

The first time that you run an incremental backup with the snapshot difference option, a snapshot is created (the base snapshot) and a traditional incremental backup is run by using this snapshot as the source. The name of the snapshot that is created is recorded in the IBM Spectrum Protect server database. The initial incremental backup must complete without failure in order for the next backup operation to use snapshot difference processing.

The second time an incremental backup is run with this option, a newer snapshot is either created, or an existing one is used (depending on the value set for the diffsnapshot option) to find the differences between these two snapshots. The second snapshot is called the diffsnapshot, or differences snapshot. The client then incrementally backs up the files that are reported as changed, by NetApp, to the IBM Spectrum Protect server. The file system that you select for snapshot difference processing must be mounted to the root of the volume. You cannot use the snapdiff option for any file system that is not mounted to the root of the volume. After you backed up the data with the snapdiff option, the snapshot that was used as the base snapshot is deleted from the snapshot directory.

On Windows systems, the snapshot directory is in ~snapshot.

On Linux systems, the snapshot directory is in .snapshot.

The client does not delete any snapshots that it did not create.

When a snapshot-differential-incremental backup operation completes, the client ensures that only the most recently-registered base snapshot persists on the filer volume. All snapshots that are created by a snapshot-differential-incremental backup on the backup-archive client begin with the characters "TSM_". If you use a snapshot tool other than the backup-archive client to produce snapshots, ensure that you do not use the string "TSM_" at the beginning of the snapshot name. If the snapshot names begin with "TSM_", the files are deleted when the client initiates the next snapshot-differential-incremental backup operation.

To run a snapshot-differential-incremental backup of read-only NetApp filer volumes, the useexistingbase option must be specified to prevent an attempt to create a snapshot on the read-only volume. Also, specify the name of the base snapshot to use (basesnapshotname option) and the name of the differential snapshot to use (diffsnapshotname option).

For NAS and N-Series file servers that are running ONTAP 7.3.0, or later, you can use the createnewbase option to back up any files that were skipped because of one of the following reasons:

• A file is excluded because the include-exclude file has an exclude rule in effect. A file is excluded when you did not change the include-exclude file, but you removed the rule that excluded the file. The NetApp API detects file changes only between two snapshots, not changes to the include-exclude file.
• If you added an include statement to the option file, that include option does not take effect unless NetApp detects that the file changes occurred. The client does not inspect each file on the volume during backup.
• You used the dsmc delete backup command to explicitly delete a file from the IBM Spectrum Protect server inventory. NetApp does not detect that a file was manually deleted from the server. Therefore, the file remains unprotected in IBM Spectrum Protect storage until it is changed on the volume and the change is detected by NetApp, signaling the client to back it up again.
• Policy changes such as changing the policy from mode=modified to mode=absolute are not detected.
• The entire file space is deleted from the IBM Spectrum Protect inventory. This action causes the snapshot difference option to create a snapshot to use as the source, and runs a full incremental backup.
• A file is excluded from backup because the file name contains a character that is not in the 7 bit-ASCII character set. The createnewbase option creates a base snapshot and uses it as a source to run a full incremental backup. NetApp controls what constitutes a changed object.

Snapshot differential backup operations are not supported in the IBM Spectrum Protect for Virtual Environments environment. You cannot run snapshot differential backup operations of a file system that resides on a NetApp filer on a host where the Data Protection for VMware or Data Protection for Microsoft Hyper-V data mover is also installed.

Table 1. Incremental command: Related options

Option	Where specified	With snapdiff
asnodename	Client system options file (dsm.sys) or command line.	Valid
asnodename	Client options file (dsm.opt) or command line.	Valid
automount	Client options file (dsm.opt).	No effect
autofsrename	Client options file (dsm.opt) only.	No effect
basesnapshotname	Client options file (dsm.opt) or command line.	Valid
basesnapshotname	Client options file (dsm.opt) or command line.	Valid
changingretries	Client system options file (dsm.sys) or command line.	No effect
changingretries	Client options file (dsm.opt) or command line.	No effect
compressalways	Client options file (dsm.opt) or command line.	Valid
compressalways	Client options file (dsm.opt) or command line.	Valid
compression	Client options file (dsm.opt) or command line.	Valid
compression	Client system options file (dsm.sys) within a server stanza, or command line.	Valid
createnewbase	Command line only.	Valid
diffsnapshot	Command line only.	Valid
diffsnapshotname	Client options file (dsm.opt) or command line.	Valid
diffsnapshotname	Client options file (dsm.opt) or command line.	Valid
dirsonly	Command line only.	Valid
domain	Client options file (dsm.opt) or command line only.	Valid
domain	Client system options file (dsm.sys), client user-options file (dsm.opt), or command line.	Valid
efsdecrypt	Client system options file (dsm.sys), client user-options file (dsm.opt), or command line.	No effect
enablelanfree	Client system options file (dsm.sys) or command line.	Valid
enablelanfree	Client options file (dsm.opt) or command line.	Valid
encryptiontype	system-options file (dsm.sys) within a server stanza.	Valid
encryptiontype	Client options file (dsm.opt).	Valid
encryptkey	Client options file (dsm.opt).	Valid
encryptkey	System-options file (dsm.sys) within a server stanza.	Valid
exclude.fs.nas	Client system options file (dsm.sys).	No effect
exclude.fs.nas	Client options file (dsm.opt).	No effect
filelist	Command line only.	Not valid
filesonly	Command line only.	Valid
followsymboliclink	Client options file (dsm.opt).	No effect
include.fs.nas	Client system options file (dsm.sys) or command line.	No effect
include.fs.nas	Client options file (dsm.opt) or command line.	No effect
inclexcl	Client system options file (dsm.sys).	Valid, but only when a file change is detected by NetApp.
inclexcl	Client options file (dsm.opt).	Valid, but only when a file change is detected by NetApp.
incrbydate	Command line only.	Not valid
memoryefficientbackup	Client options file (dsm.opt), server, or command line.	No effect
memoryefficientbackup	This option is allowed in both dsm.sys and dsm.opt, but the value in dsm.opt is ignored if it is also in dsm.sys. You can also place this option within a server stanza, or on the initial command line.	No effect
monitor	Command line only.	Not valid
nojournal	Command line only.	Not valid
nojournal	Command line only.	Not valid
postsnapshotcmd	Client system options file (dsm.sys) or with the include.fs option.	Valid
postsnapshotcmd	Client options file (dsm.opt) or with the include.fs option.	Valid
preservelastaccessdate	Client user-options file (dsm.opt) or command line.	Valid
preservelastaccessdate	Client options file (dsm.opt) or command line.	Valid
presnapshotcmd	Client system options file (dsm.sys) or with the include.fs option.	Valid
presnapshotcmd	Client options file (dsm.opt) or with the include.fs option.	Valid
removeoperandlimit	Command line only.	Valid
resetarchiveattribute	Client options file (dsm.opt).	Valid
skipaclupdatecheck	Client options file (dsm.opt).	Valid
skipntpermissions	Client options file (dsm.opt) or command line.	Valid
skipntsecuritycrc	Client options file (dsm.opt) or command line.	Valid
snapdiffhttps	Command line only.	Valid
snapshotcachesize	Client system options file (dsm.sys) or with the include.fs option.	No effect
snapshotproviderfs	System-options file (dsm.sys) within a server stanza or with the include.fs option.	Not valid
snapshotproviderfs	Client options file (dsm.opt) or with the include.fs option.	Not valid
snapshotproviderimage	Client system options file (dsm.sys) or with the include.image option.	Not valid
snapshotproviderimage	Client options file (dsm.opt) or with the include.image option.	Not valid
snapshotroot	Command line only.	Not valid
subdir	Client options file (dsm.opt) or command line.	Not valid
tapeprompt	Client options file (dsm.opt) or command line.	Valid
tapeprompt	Client options file (dsm.opt) or command line.	Valid
toc	Command line only.	Not valid
toc	Command line only.	Not valid
useexistingbase	Command line only.	Valid
useexistingbase	Command line only.	Valid
virtualfsname	Command line only.	Not valid
virtualmountpoint	Client system options file (dsm.sys).	Not valid