Using MultiSite for Interoperability


You can use multiple replicas in local area networks to provide native access to VOBs in a heterogeneous network. The following sections describe MultiSite support for multiple replicas in a LAN and give setup instructions.

Advantages and Disadvantages

Advantages of using MultiSite for interoperability:

Disadvantages of using MultiSite for interoperability:

Restrictions on Multiple Replicas in a LAN

You must observe these restrictions when you create multiple replicas in a LAN:

Caution: Do not use MultiSite to create multiple copies of a VOB in a single ClearCase region. Because the VOB UUID is identical for all replicas in a VOB family and is stored in many structures in a VOB, there is no way to make the copy of the VOB unique. Creating and mounting multiple copies of a VOB in a single region causes clearmake and views to exhibit unpredictable behavior, may cause data loss, and is not supported by Rational Software.

Setting Up Multiple Replicas at One Site

This section describes the process of creating multiple replicas at one site.

Creating a replica of an existing VOB doesn’t split the storage. On the contrary, the new replica requires additional disk space to accommodate another complete copy of the VOB’s database and storage pools. For information about relocating VOB data, see the Administrator’s Guide for Rational ClearCase.

If both replicas are on UNIX hosts or in the same Windows domain, they can preserve identities. Any change in the owner, group, or access mode of an element at one of the replicas is propagated to the other replica.

The following procedure creates a Windows replica from a UNIX replica:

  1. On the UNIX host:
  2. multitool mkreplica –export –work /tmp/ms_wkdir –fship 
    –c "create replica for Windows use" aquarium:boston_windows 
    Generating replica creation packet 
    /opt/rational/clearcase/shipping/ms_ship/outgoing/repl_boston_hub_2
    3-Dec-02.13.16.43_21767_1 
     - shipping order file is 
    /opt/rational/clearcase/shipping/ms_ship/outgoing/sh_o_repl_boston_
    hub_23-Dec-02.13.16.43_21767_1
    Dumping database...
      . . .
    Dumper done.
    Attempting to forward/deliver generated packets...
      -- Forwarded/delivered packet 
    /opt/rational/clearcase/shipping/ms_ship/outgoing/repl_boston_hub_2
    3-Dec-02.13.16.43_21767_1 
  3. On the Windows host:
  4. multitool lspacket –short 
    c:\Program Files\Rational\ClearCase\var\shipping\ms_ship\incoming\r
    epl_boston_hub_23-Dec-02.13.16.43_21767_1
    multitool mkreplica –import  –npreserve –work c:\tmp\msite 
    -tag \dev –public –vob \\aquarium\vobs\dev.vbs 
    c:\Program Files\Rational\ClearCase\var\shipping\ms_ship\incoming\repl
    _boston_hub_23-Dec-02.13.16.43_21767_1 
    The packet can only be used to create replica "boston_windows"
      - VOB family is ecf68c58.90fe11cd.a393.08:00:09:49:29:cd
      - replica OID is 9947c591.912d11cd.a4b1.08:00:09:49:29:cd
    Should I create this replica? [no] yes
    Comments for "boston_windows":
    provide native Windows access to VOB
    .
    Processing packet 
    c:\Program Files\Rational\ClearCase\var\shipping\ms_ship\incoming\r
    epl_boston_hub_23-Dec-02.13.16.43_21767_1
    ...