vob_snapshot_setup

Sets or displays VOB database snapshot parameters

Applicability

Product

Command type

ClearCase®

command

Platform

UNIX®
Linux®

Windows®
Parent topic: Backing up and restoring VOBs
Parent topic: Rational ClearCase command reference

Synopsis

Description

Use vob_snapshot_setup to control VOB database snapshot activity on each VOB host. By default, the scheduler runs vob_snapshot periodically. When vob_snapshot runs on a VOB host, it checks each locally stored VOB for the existence of a multipart string attribute that specifies snapshot parameters. A VOB's database is copied by vob_snapshot only if this attribute has been applied to the VOB with vob_snapshot_setup. Use vob_snapshot_setup lsvob to list the local VOBs currently processed by vob_snapshot and, with –long, to display the snapshot parameters for each VOB in the list.

Use vob_snapshot_setup modparam to add a VOB to the database snapshot list, or to change snapshot parameters for a VOB already on the list. (You cannot modify individual parameters with modparam, but must replace them all.)

Use vob_snapshot_setup rmparam to remove a VOB from the snapshot list.

See also vob_snapshot and vob_restore.

Important: Do not run vob_snapshot_setup on a V2.x VOB, until you have reformatted the VOB for V3 with reformatvob, and you are certain that checkvob –setup has completed successfully. checkvob –setup updates storage container names and verifies the presence of V3 type managers. If either operation fails, checkvob cannot synchronize a database snapshot at vob_restore time. If you are using a homegrown or third-party type manager, code that implements the get_cont_info method must be added to the type manager so that elements managed by the type manager can be processed by checkvob at vob_restore time.

Setting VOB snapshot parameters

An administrator uses vob_snapshot_setup modparam to apply the following snapshot parameters to each VOB or replica for which database snapshots are to be taken:

Parameter

Valid Values

Default Value

–snap_to

Existing, writable directory pathname

No default

–dbcheck

yes | no

No

–notify (UNIX and Linux only)

Comma-separated list

Empty list

These parameters are combined to form a single string attribute of type vob_snapshot_parameters, which vob_snapshot_setup attaches to the VOB.

Here is how these parameters may appear in a vob_snapshot_setup lsvob –long listing:

VobTag:                  /vobs/src
...
Dbcheck Enabled:         yes
Notification List:       root user,clearadm,anne
Snap To:                 /net/saturn/usr1/snapshots
...

For more information, see the –snap_to, –dbcheck, and –notify options.

Disk space used

The VOB snapshot backup/restore scenario requires additional disk space, both at restore time and during daily operation:

  • At restore time, checkvob may require substantial disk space. See the checkvob reference page.
  • Enabling VOB snapshots for a VOB also enables a deferred source container deletion mechanism, which typically increases source pool size. For a description of deferred deletion, see the IBM Rational ClearCase Administrator's Guide.

Restrictions

Identities

On UNIX and Linux, you must be VOB owner or root. On Windows, no special identity is required.

Locks

With the modparam and rmparam operations, an error occurs if one or more of these objects are locked: VOB, vob_snapshot_parameters attribute type.

Mastership

(Replicated VOBs only) The VOB replica must be self-mastering.

Options and arguments

VOB listing report format

Default
vob_snapshot_setup lsvob lists the VOB tag of each local VOB currently configured for database snapshot.
–short
Same as default.
–long
In addition to the VOB tag, vob_snapshot_setup lsvob lists each VOB's snapshot parameters and additional VOB identity details. If multiple VOBs use the same parent –snap_to directory, use the replica UUID returned by –long to find a particular snapshot in the parent directory.
vob-tag ...
Space-separated list of VOBs; restricts listing to one or more local VOBs.

Specifying the VOB

Default
None. modparam and rmparam operations require a VOB tag argument.
vob-tag
The VOB's VOB tag, as specified in mkvob or mktag –vob.

Setting snapshot parameters

Default
With modparam, you must specify a VOB tag; if you specify no other options or arguments, modparam prompts for all necessary input and displays explanatory text. If you specify both a VOB tag and a snapshot target directory, modparam does not prompt for additional parameters: vob_snapshot does not run the db_check operation, and the notify list is empty.
–snap_to snap-dir-pname
A disk location to store the snapshot. vob_snapshot appends the VOB's replica UUID to the –snap_to directory to create a subdirectory, then copies the VOB database to the subdirectory (after checking for sufficient disk space).

The replica UUID subdirectory that stores a VOB's database snapshot is overwritten the next time vob_snapshot processes that VOB.

Typically, the –snap_to directory gets backed up as part of normal backup operations some time after the snapshots are taken.

–dbcheck yes, –dbcheck no
Specifies whether to run the db_check utility on each snapshot.

vob_snapshot runs db_check to perform fundamental database consistency and integrity checks. (Later, at restore time, checkvob may examine the VOB database looking for ClearCase anomalies.) The db_check pass occurs after all snapshots are completed on the local host. Because this check can be time-consuming, it is disabled by default.

If vob_snapshot cannot lock the database and db_check is disabled, db_check runs on the snapshot at vob_restore time. Running db_check earlier, at snapshot time, may expose problems that you do not want to encounter at recover time.

–notify login-name[,...]
A list of user IDs to be notified when vob_snapshot processes this VOB or replica. This VOB-specific list supplements the per host notification list maintained in /var/adm/rational/clearcase/config/snapshot.conf. The snapshot.conf file also specifies the notification program to be used. If you do not want to supply a list of user IDs to be notified, specify –notify "''" on the command line.

Examples

  • On a UNIX or Linux system, list all VOBs on the local host that are currently configured for processing by vob_snapshot.

    /opt/rational/clearcase/etc/vob_snapshot_setup lsvob /vobs/src
    /vobs/lib

  • Same as previous example, but expand the output to include each VOB's replica UUID and snapshot parameters. And this is run on a Windows system.

    cd c:\Program Files\IBM\ClearCase\etc
    vob_snapshot_setup lsvob –longVobTag: \vob_src
    Replica Name:            original
    Replica Uuid:            4a6bbe5d88d511cfa9b400018073db6f
    Family  Uuid:            4a6bbe5988d511cfa9b400018073db6f
    Dbcheck Enabled:         yes
    Snap To:                 \\saturn\bigdisk\snapshot
    Deferred Deletes:        Enabled

    VobTag: \vob_lib
    Replica Name:            original
    Replica Uuid:            5fec90f48db911cfab9800018073db6f
    Family  Uuid:            5fec90f08db911cfab9800018073db6f
    Dbcheck Enabled:         no
    Snap To:                 \\saturn\bigdisk\snapshot
    Deferred Deletes:        Enabled

  • On a Windows system, add VOB \vob_src to the local host's snapshot list.

    cd c:\Program Files\IBM\ClearCase\etc

    vob_snapshot_setup modparam  –dbcheck yes
    –snap_to \\saturn\bigdisk\snaps\vob_src       \vob_src

  • Add /vobs/src to the local host's snapshot list, as in the previous example, but this time run vob_snapshot_setup modparam in interactive mode on a UNIX or Linux system.

    vob_snapshot_setup modparam /vob/src

    Supply a directory to contain the snapshot data for this vob.
    The directory must exist and be writable.
    (Full pathname: there is no default)     /net/saturn/usr1/snaps/src

    Supply a comma separated list of those users to be notified of
    events during the snapshot of this vob.
    (Comma separated user id list: default no one):     root,clearadm,anne

    Do you want a data base check to be performed on this vob after
    all snapshot operations on this host are completed?
    Valid responses are (yes,no)
    The default is no:     yes

  • On a Windows system, remove VOB \vob_src from the local host's snapshot list.

    cd c:\Program Files\IBM\ClearCase\etc
    vob_snapshot_setup rmparam \vob_src

UNIX and Linux files

  • /var/adm/rational/clearcase/config/snapshot.conf
  • /var/adm/rational/clearcase/log/snapshot_log

Windows files

  • ccase-home-dir\var\log\snap_log

Windows NT® registry keys

HKEY_LOCAL_MACHINE\SOFTWARE
  • \Atria\ClearCase\CurrentVersion\snapshot
Feedback