2.3 Choosing a Location and Name

For a snapshot view, the View Creation Wizard prompts you to choose a location for the view. For a dynamic view, the wizard prompts you to choose a name, drive letter, and, the first time you create a dynamic view, a location for the view storage directory.

Snapshot View: Choosing a Directory

When creating a snapshot view, you must specify a directory into which ClearCase loads (copies) files and directories. When choosing a directory for the view, consider these constraints:

• The view's root directory must be located on a disk with enough space for the files loaded into the view and any view-private files you add.

• Your organization may restrict where you can create a view. For example, you may be required to use a disk that is part of a data-backup scheme.

• If you want to access the view from other computers, it must be located in a shared directory.

If your makefiles or other files require absolute pathnames with a specific drive letter, assign the view to a drive letter. See Assigning Snapshot Views to Drive Letters.

Under the Hood: A Snapshot View Storage Directory

Every snapshot view has a view storage directory in addition to the directory tree of source files that it loads from VOBs. ClearCase uses the snapshot view storage directory to keep track of such information as which files are loaded into your view and which versions are checked out to it. The view storage directory is for ClearCase administrative purposes only. Do not modify anything in it.

For every 1,000 elements loaded into the view, ClearCase uses about 400 KB of disk space for the view storage directory.

Locations for Snapshot View Storage Directories

Usually, your ClearCase administrator sets up a storage location, which is a directory on a ClearCase server host on UNIX or Windows. By default, ClearCase locates snapshot view storage directories there. If your ClearCase administrator sets up more than one storage location, ClearCase selects any one of these locations as the default when you create a view.

If your ClearCase administrator does not set up storage locations, by default, ClearCase software locates the view storage directory under the root directory of the snapshot view.

You can override these defaults. If your administrator sets up multiple storage locations, you can select one explicitly. If your ClearCase host is set up to store view storage directories (which happens when you install ClearCase), you can place the view storage directory under the root directory of the snapshot view. Or you can choose another location.

If you place the view storage directory under the root directory of the view, be aware of the following recommendations:

• Do not choose this configuration if you use the view when disconnected from the network. You can corrupt the data in the view storage directory if you disconnect it from the network while the view's view_server process is running.

• Make sure that the view storage directory is accessible to any data backup schemes your organization institutes.

If you override the default and place the view storage location under a directory other than the root directory of the view, the directory must be below a shared network directory on a ClearCase host running Windows NT or Windows 2000 and must remain connected to the network. (A view process runs on the machine that physically stores the view storage directory, and only a ClearCase host running on Windows NT or Windows 2000 can run a view process.) The pathname for the directory must not use a Windows special share name, for example, the share that is designated by drive-letter$ and allows an administrator access to a drive over the network. The directory cannot be on a removable storage device or on a laptop.

NOTE: If you plan to work while disconnected from the network, or if your ClearCase host is not set up to store view storage directories, your administrator must set up storage locations.

To Override the Default Value for a Snapshot View Storage Location

1. When creating a view, on the step of the wizard that asks you to choose a location for a snapshot view, click Advanced Options.

2. In the Advanced View Options dialog box, do one of the following:

• If Use Server Storage Location is selected and your administrator created multiple locations, ClearCase selects one for you. To choose a different one, click the name of the location.

• If your computer is set up to store view storage directories and you want to locate the view storage directory in the root directory of the snapshot view or choose another location, select Use explicit path.

Do not select this option if you plan to use the view while disconnected from the network.

3. If you select Use explicit path, do one of the following:

• Accept the default path displayed in the View storage location box.

• Edit the path in the View storage location box to specify a valid location.

• Click Browse and choose a valid location.

4. Click OK to return to the view location step of the wizard.

Choosing a View Name

Each view must have a descriptive name (called a view-tag) that is unique within a network region. For dynamic views, the View Creation Wizard suggests a view-tag based on the following convention: username_view. This name is designed to help you determine the owner and purpose of the view. Names like myview or work do not describe the view's owner or contents; if you work with more than one view, such generic names can lead to confusion. Here are some suggested names:

A view's name must be a simple name; that is, it must follow the format of a single file or directory name with no special characters or spaces.

Dynamic View: Choosing a Drive Letter

If your makefiles or other files require absolute pathnames, assign your view to a drive letter. When you use a wizard to create a view, ClearCase prompts you to assign the dynamic view to a drive letter. After creating a view, if you want to change a drive-letter assignment or assign a drive letter to a team member's view, you can create or modify the assignment while adding a view shortcut to ClearCase Explorer.

In addition, you can create or modify drive-letter assignments from Windows Explorer. Any changes you make to a view's drive-letter assignments outside ClearCase Explorer will invalidate the view's shortcut in ClearCase Explorer.

Pathname Differences

In Windows Explorer, you can access any dynamic view that is started on your computer from the dynamic-views-drive (by default, drive M). However, when you access a view from the dynamic-views drive, its pathname includes one more component than when you access a view from an assigned drive letter (Figure 9).

For example, both of the following pathnames are available to an element in the pat_v1.4_cropcircle dynamic view that is assigned to drive P:

M:\pat_v1.4_cropcircle\guivob\lib.c
P:\guivob\lib.c

Figure 9 Dynamic Views Started on a Host

Dynamic View Storage Directories

If this is the first time you're setting up a dynamic view, ClearCase prompts you to choose a shared directory on your host as a location for the view storage directory. For dynamic views you create subsequently, ClearCase uses this location by default.

Every view has a view storage directory. For dynamic views, ClearCase uses this directory to keep track of which versions are checked out to your view and to store view-private objects. The view storage directory is for ClearCase administrative purposes only. Do not modify anything in it.

The size of the view storage directory depends on the following factors:

• Whether you use the clearmake or omake build auditing and build avoidance features

• The size and number of view-private files

For more information, refer to the Administrator's Guide for Rational ClearCase and to the clearmake and omake reference pages in the Command Reference.

Choosing Locations for Dynamic View Storage Directories

If your computer is set up to store view storage directories, ClearCase reduces communication over the network by locating the view storage directory on your computer.

Consider the following restrictions when choosing a dynamic view storage directory location:

• The directory must be a subdirectory of a shared network resource on a ClearCase host on Windows NT or Windows 2000. View processes (specifically, view_server processes) run on the computer that physically stores the view storage directory, and only ClearCase hosts on Windows NT can run view processes. The pathname for the directory must not use a Windows special share name. Special share names usually include the dollar sign ($), such as the driveletter$ share name that allows an administrator to gain access to a drive over the network. For example, \\bread\c$\view\pat_1.4_cropcircle.vws is not a valid pathname.

• To maintain data integrity, the view storage directory must remain connected to the network. For example, do not locate the view storage directory on a removable storage device.

• If you locate the view storage directory on a laptop and then disconnect the laptop from the network, all of the following restrictions apply:

• You cannot use the dynamic view.

• Team members who try to start your view from their hosts will receive error messages from ClearCase.

• Any clearmake or omake process that attempts to wink in a derived object from your view will spend some amount of time trying to contact your view. If it cannot contact your view, it will not consider derived objects in your view as winkin candidates for 60 minutes. (You can change the amount of time by setting the CCASE_DNVW_RETRY environmental variable.) For more information, see the clearmake reference page.

• If your ClearCase administrator sets up storage locations (which are directories on ClearCase server hosts), you can locate your dynamic view storage directory in a storage location. However, for best performance, we recommend that you locate dynamic view storage directories on your local host.

We recommend that you make the view storage directory accessible to any data backup schemes your organization institutes.

To Choose a Location for a Dynamic View Storage Directory

1. On the step of the wizard that asks you to choose a name and drive for a dynamic view, click Advanced Options.

2. In the Advanced View Options dialog box, do one of the following:

• Select Use Explicit Path and provide a UNC pathname to a shared directory on a ClearCase host on Windows NT. For best performance, we recommend this option.

The first time you create a view with the wizard, ClearCase presents a template: \\current-hostname\<Share>\view-tag.vws

To locate the view storage directory on your computer (recommended), replace <Share> with the name of a shared directory on your computer. For example,
\\bread\view_storage\pat_v1.4_cropcircle.vws

• Select Use Server Storage Location. If your administrator created more than one location, ClearCase selects one for you. You can choose a different one if you prefer.