Using the snapdiff option with the incremental command streamlines the incremental backup process. The command runs an incremental backup of the files that were reported as changed by NetApp instead of scanning all of the volume for changed files.
The snapdiff option
is for backing up NAS/N-Series file server volumes that are NFS or
CIFS attached.
Restriction: None
of the NetApp predefined shares, including C$, works
with the Tivoli® Storage Manager
snapshot difference option because Tivoli Storage
Manager client cannot determine their mount points programmatically. 
You must configure a user ID and password
on the Tivoli Storage Manager
client to enable snapshot difference processing.
Use this option with an incremental backup
of a NAS file server volume instead of a simple incremental or incremental
with snapshotroot whenever the NAS file server is
running ONTAP 7.3.0, or later, for performance reasons. Do not use
the snapdiff and snapshotroot options
together.
Restriction: Incremental backups with snapshot
difference processing are only available with the Tivoli Storage Manager 64-bit AIX® client and the Tivoli Storage Manager Linux x86_64 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 Tivoli Storage Manager 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 to find the differences between these two snapshots. The second
snapshot is called the diffsnapshot. Tivoli Storage Manager then incrementally
backs up the files reported as changed by NetApp to the Tivoli Storage Manager 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 AIX and Linux systems, the snapshot directory is in .snapshot. Tivoli Storage Manager does not
delete the snapshot if it was not created by Tivoli Storage Manager. You can also run a
snapshot-difference incremental-backup by specifying the -diffsnapshot=latest option.
To run a snapshot differential 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. Tivoli Storage Manager does not inspect each file on the volume during backup.
- You used the dsmc delete backup command to explicitly delete a file from the Tivoli Storage Manager inventory. NetApp does not detect that a file was manually deleted from Tivoli Storage Manager. Therefore, the file remains unprotected in Tivoli Storage Manager storage until it is changed on the volume and the change is detected by NetApp, signaling Tivoli Storage Manager 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 Tivoli Storage Manager 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.
- Valid
- Processing runs normally when the option is used.
- Not valid
- If the option is used with the snapdiff option, an error message is generated.
- No effect
- The option can be used, but it is ignored.
| 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 |
| subfilebackup |
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 |
Supported Clients
- All Windows clients
except IA® 64 bit
- AIX 64-bit
clients
- Linux x86_64
clients
Parameters
There are no parameters for this option.
Examples
- Command line:
- Perform a snapdiff incremental backup of an NFS mounted file system /vol/vol1 hosted on the file server homestore.example.com, where /net/home1 is the mount point of /vol/vol1.
- incremental -snapdiff -diffsnapshot=latest /net/home1
- Command line:
- Perform a snapdiff incremental backup from a snapshot that is taken of a network share //homestore.example.com/vol/vol1 mounted on drive H:, where homestore.example.com is a file server.
- incremental -snapdiff H:
- Perform a snapdiff incremental backup from a snapshot that is taken of a network share //homestore.example.com/vol/vol1 mounted on drive H:, where homestore.example.com is a file server. The -diffsnapshot option value of LATEST means that the operation uses the latest snapshot (the active snapshot) for volume H:.
- incremental -snapdiff H: -diffsnapshot=latest
- Command line:
- Run a one-time full incremental backup after detecting that the
NetApp server has migrated to a unicode-enabled file server from a
server that did not support unicode file names.
dsmc incremental -snapdiff -createnewbase=migrate /net/home1 dsmc incremental -snapdiff -createnewbase=migrate h: - Run a snapshot difference incremental backup after detecting that
the NetApp server has migrated to a unicode-enabled file server from
a server that did not support unicode file names. This command suppresses
the warning message.
dsmc incremental -snapdiff -createnewbase=ign /net/home1 dsmc incremental -snapdiff -createnewbase=ign h: - Perform a full incremental backup because you made some include
or exclude changes:
dsmc incremental -snapdiff -createnewbase=yes /net/home1 dsmc incremental -snapdiff -createnewbase=yes h: