c-treeACE Server Files

The c-treeACE Server creates special system files to maintain various kinds of information required to recover from problems. The following list details exactly what files are created, along with all required information needed by the System Administrator responsible for working with them. As the Administrator, be sure these files are backed up when appropriate and used for recovery when necessary.

Note: To be compatible with all operating systems, the names for all these files are upper case characters.

c-treeACE Server Status Log

When it starts up, and while running, the c-treeACE Server keeps track of critical information concerning the status of the c-treeACE Server, e.g., when it started; whether any error conditions have been detected; and whether it shuts down properly. This information is saved in

chronological order in a text file, the c-treeACE Server Status Log, CTSTATUS.FCS. To control

the size of CTSTATUS.FCS, or to maintain inactive logs as T*.FCS files, use the

Backups and Data Integrity

Administrative Information Tables

The c-treeACE Server creates and uses the file FAIRCOM.FCS to record administrative

information concerning users and user groups. This file can be encrypted with the

ADMIN_ENCRYPT keyword. See "Configuring the c-treeACE Server" (page 148) for details. Transaction Management Files

I0000002.FCS is an empty file generated at startup by any c-tree database engine with

transaction support enabled. This file marks ownership of the process directory to avoid colliding with other c-treeACE processes that may generate their own independent transaction log files.

The dump restore utility (ctrdmp) is the most common case where this is reported. When one

running process detects this file, a TCOL_ERR error (537) is returned indicating this collision.

Note: It is important to safeguard these files, however only the S*.FCS and D0000001.FCS files should remain after a normal server shutdown.

File Name Mapping

c-treeACE maintains a mapping of file names to file numbers. This is transient information and

stored in the D0000000.FCS file.

The c-treeACE Server creates the following files for managing transaction processing: I0000001.FCS

Delete Node Queue

D0000001.FCS maintains a list of emptied index nodes. These are eventually cleaned up by the delete node thread and remain available for reuse if needed via this queue.

Active Transaction Logs

Information concerning ongoing transactions is saved on a continual basis in a transaction log file. A chronological series of transaction log files is maintained during the operation of the

c-treeACE Server. Transaction log files containing the actual transaction information are saved as

standard files. They are given names in sequential order, starting with L0000001.FCS (which can

be thought of as “active c-treeACE Server log, number 0000001”) and counting up sequentially (i.e., the next log file is L0000002.FCS, etc.).

The c-treeACE Server saves up to four active logs at a given time. When there are already four active log files and another is created, the lowest numbered active log is either deleted or saved as an inactive transaction log file, depending on how the c-treeACE Server is configured (see inactive transaction logs).

Every new session begins with the c-treeACE Server checking the most recent transaction logs (i.e., the most recent 4 logs, which are always saved as “active” transaction logs) to see if any transactions need to be undone or redone. If so, these logs are used to perform an automatic recovery. When configuring the c-treeACE Server, the odd and even numbered logs can be written to different physical devices. See "Configuring the c-treeACE Server" (page 148). Checkpoint Files

S00000000.FCS and S0000000.FCS are generated during transaction log checkpoints. These files are used to "kick start" recovery and point to known good transaction states.

Backups and Data Integrity

Inactive Transaction Logs

Transaction log files no longer active (i.e., they are not among the 4 most recent log files) are deleted by default. To save inactive transaction log files when new active log files are created,

add the KEEP_LOGS configuration option to the server configuration with a positive number

indicating the number of logs to keep. In this case, an inactive log file is created from an active log file by renaming the old file, keeping the log number (e.g., L0000001) and changing the file’s

extension from “.FCS” to “.FCA.” The Administrator may then safely move, delete, or copy the

inactive, archived transaction log file. Temporary Stream Files

The server creates five stream files at startup. These files prevent errors when the operating system has used a large number of file handles and the server needs a stream file. The file

names begin with FREOPEN followed by a distinguishing character and ending with .FCS. These

temporary files are used for internal server operations and should automatically be deleted during a normal server shutdown.

Optional Server System Event Log

The c-treeACE Server maintains two optional system files: SYSLOGDT.FCS and

SYSLOGIX.FCS. SYSLOGDT.FCS is a c-treeACE data file with a record for each recordable

system event. Unlike the CTSTATUS.FCS file, the system log files can be encrypted so entries

cannot be added, deleted, or modified with a simple text editor, and vendors can add application specific entries to the log. See "Configuring the c-treeACE Server" (page 148) or your vendor’s

documentation for information on the SYSLOG (page 133) keywords appropriate to your application.

In case of a system failure, be sure to save all the system files (i.e., the files ending with “.FCS”).

CTSTATUS.FCS may contain important information about the failure. When there is a system catastrophe, such as a power outage, there are two basic possibilities for recovery:

 When the power goes back on, the system will use the existing information to recover

automatically.

 The Administrator will need to use information saved in previous backups to recover (to the

point of the backup) and restart operations.