Caché System Administration Guide
Using Caché on UNIX®, Linux, and Mac OS X
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This chapter describes specific administrative procedures on UNIX®, Linux, and Mac OS X. This chapter addresses the following topics:

UNIX® Users, Groups and Permissions
Every Caché installation on a UNIX® platform has the following users and groups:
Note:
These settings are maintained, in part, as the set of permissions on the executables within the install-dir/bin directory of the Caché installation. Relevant properties include: ownership, group, mode, set-uid, and set-gid bits. It is important that you do not modify these permissions when performing administrative tasks at the operating-system level.
Database and Database Directory Permissions
All databases and database directories must have the group ownership set to the Effective group for Caché processes group and grant full permissions to that group (rw for databases, rwx for database directories). The user who owns the databases and database directories may vary depending on how they were created.
Databases and database directories created within Caché are created with the appropriate permissions. However, if you move, copy or create database directories or databases externally (via scripts or administrator action), you must ensure that the proper permissions are maintained. Failure to set the permissions properly may lead to unexpected and serious errors.
The following example assumes the Effective group for Caché processes is cacheusr and the Owner of instance is cacheowner, although the files may have different user ownership depending on the context in which they were created:
dataset directory    cacheowner    cacheusr    drwxrwxr-x 
CACHE.DAT            cacheowner    cacheusr    -rw-rw----
Startup on UNIX®
The Caché instance uses the following resources to control starting, stopping, and creating new processes:
  1. The cache.ids file in the install-dir\mgr directory.
  2. Shared memory.
Daemon Resource Locks
Caché uses advisory file locking to prevent multiple startups of the same instance on different machines. With advisory file locking, a single lock file (in this case, the file clock in the install-dir/bin directory) may be used to exclusively lock multiple resources. The Control Process, Write daemon, and Journal daemon each lock a separate section of the lock file. If this section of the clock file is already locked, startup terminates. The locks held by the different daemons are called Daemon Resource Locks.
A file lock is held by a process until the process terminates. Thus if any lock is held, it indicates that some daemon process on some node is running. It does not indicate, however, whether or not the instance is healthy and running normally.
Cache.ids File
The cache.ids file contains the name of the node where Caché was started. Although the existence of the cache.ids file acts as a flag to Caché utilities and customer-written scripts – indicating whether or not the instance is up and running – this file is largely ignored during startup. In previous versions of Caché, the shared memory identifiers were also stored in the cache.ids file, but this is no longer the case.
Startup Sequence
To best understand the startup sequence, imagine that the instance can be run from two (2) different nodes (machines), node A and node B. The cache.ids file is visible to both nodes, as are the Daemon Resource Locks (for shared files). The shared memory itself, however, is visible only on the node on which it was created (that is, the node where you started Caché).
Step 1. Check the Status of the Instance
The startup routine runs cache –cV to find out the status of the instance. It first attempts to attach to shared memory for the instance:
Step 2. Start Caché
The Caché startup process (cache) is run. Checks are repeated to ensure that another startup is not competing for the startup resources:
Caché continues startup.
Managing Caché
From the shell, a user with any user ID in the sysmgr group can run ccontrol (see Controlling Caché Instances in the “Using Multiple Instances of Caché” chapter) which invokes Caché executables and scripts in the install-dir/bin directory. The following sections describe how to perform these management tasks on a Caché instance:
Important:
The owner of the installation has full privileges to start and stop the instance, to perform system administration, and to run diagnostic programs for that instance.
Only the user ID that is the owner of the instance can and should run all diagnostic activities. This ensures that any files or resources created are owned by the owner of the instance and not root (which may make it impossible to access these resources by a non-root user). For this reason, it is inadvisable for root to in any way administer an instance not owned by root (including starting and stopping the instance). A user running as root should only administer instances owned by root.
Starting Caché
To start Caché, run the startup procedure at the system level. This procedure activates either a default configuration file or a configuration file you specify.
Note:
If you have any trouble starting Caché, view the cconsole.log file as described in the Monitoring Log Files section of the Caché Monitoring Guide.
If you are not on the console machine, run Telnet and connect to the target machine where Caché is installed. Before you can start Caché on UNIX®, one of the following must be true:
Start Caché using the ccontrol command:
ccontrol start <instname>
where instname is the name of the Caché instance you want to start. See Controlling Caché Instances in the “Using Multiple Instances of Caché” chapter of this guide for more options and information.
From the shell, a user with any user ID in the sysmgr group can run ccontrol start. This command verifies that the instance is not currently running on the current or another node, creates shared memory and basic Caché daemons, including multiple slave write daemons (SWDs), runs the startup (^STU) routine, which creates additional daemons (for example, ECP daemon), and then allows user logins.
Running Caché
From the shell, a user with any user ID and any group ID (anyuser:anygroup in this example), can run csession (see Connecting to a Caché Instance in the chapter “Using Multiple Instances of Caché”) which executes cuxsession in the install-dir/bin directory.
Running as anyuser:cacheusr, Caché runs its standard startup logic, including Kerberos negotiation, to identify a $USERNAME and a set of login roles. In many cases, this $USERNAME value is associated with the actual user who invoked csession. Thus, while any user may run Caché, the activities of that user once in Caché are defined and limited by the security roles assigned to that user.
Caution:
Do not enter Caché by invoking its executable (cache.exe) directly from the install-dir/bin directory.
The Caché executable is not itself a setgid-executable. It is the responsibility of the csession wrapper to set the group properly on behalf of the user entering Caché. This is not a problem if you are running Caché from the /usr/bin directory as set up by the ccontrol default function. The ccontrol default sets up an executable file called cache in the /usr/bin/ directory and is a link to call csession which sets permissions properly.
Note:
On Mac OS X 10.11 and later, ccontrol and csession are located in /usr/local/bin, with links from /usr/bin.
Stopping Caché
Normally you leave your Caché system running. However, if your operating system requires a restart, you should stop Caché before you shut down your system. The Caché maintenance tasks, such as backups and database repair utilities, do not require you to stop Caché.
To stop Caché on UNIX®, the same requirements exist as for starting Caché. One of the following must be true:
To stop Caché, from the command line:
  1. Use the ccontrol stop command:
    ccontrol stop <instname>
    
    where instname is the name of the Caché instance you want to stop. (See Controlling Caché Instances in the “Using Multiple Instances of Caché” chapter of this guide for more ccontrol options and information.)
    Caution:
    You can stop Caché with the ccontrol force command, but you should do so with caution because it may result in a loss of data.
  2. This procedure invokes the Caché SHUTDOWN utility, which displays a status report. Check for active processes in the report to determine if the next step is necessary.
  3. Should it be necessary, broadcast a message to any users on the system:
    Do you want to broadcast a message to anyone? No=> Yes
    Send a message to other terminals. Message => Please sign off
    Terminal => /dev/tty/06
    Terminal =>
    Message =>
    
  4. After sending one message you can send others, until you respond to the Message prompt by pressing Enter.
  5. When the system asks if you would like to see another system status, enter Yes to see one, or press Enter if you do not want another report.
  6. If you answer Yes, when the system status displays again, identify any active terminals.
  7. Confirm that you want to halt by answering Yes. If you answer No, the shutdown procedure quits and Caché continues running.