HP Eloquence A.06.20 / Release Notes

Database Server (eloqdb6) Enhancements

Server Configuration changes
HTTP Performance display
On-line backup
dbctl command line interface to eloqdb6

Server Configuration changes

The following configuration changes are present in the eloqdb6.cfg configuration file. When updating from a previous HP Eloquence version, please review the new eloqdb6.cfg configuration template file and merge relevant changes manually to your current eloqdb6.cfg configuration file.

On the HP-UX and Linux platforms, the eloqdb6.cfg configuration file is located at /etc/opt/eloquence6/eloqdb6.cfg
The default eloqdb6.cfg configuration file is located at /opt/eloquence6/newconfig/config/eloqdb6.cfg

On the Windows NT platform, the eloqdb6.cfg configuration file is located at <Installation Directory>/etc/eloqdb6.cfg
The default eloqdb6.cfg configuration file is located at <Installation Directory>/etc/eloqdb6.cfg.sam

Please note: On the HP-UX and Linux platform, the eloqdb6 I/O processes or kernel threads are visible by ps. So instead of a single eloqdb6 you will have 5 eloqdb6 processes running by default. This is normal.

[server] section

Title = "Title"

If set, a server title is displayed by the ps program in the eloqdb6 command line instead of the default "eloqdb6: active". If you are using multiple eloqdb6 server processes on a single system this can be used to distinguish between different server instances. The default value is empty. This configuration is ignored on the Windows NT platform.

NoDNS = {0|1}

If set, no reverse DNS lookup is performed on connection to the eloqdb6 server. A broken DNS configuration or a slow DNS server could lead to long connection times. Default value is 0.

DisableScan = {0|1}

If set, the eloqdb6 scan API (which is used to accelerate the FIND/SORT command and used by SQL/R) is disabled. The only reason to set this configuration item is to track a possible problem in the FIND/SORT command (which then falls back to the older, much slower access strategy). The default value is 0.

SyncMode = {0|1}

If set (the default), this causes the eloqdb6 server to operate in sync write mode. The sync write mode is more resistent against operating system and hardware failures. When sync mode is disabled (set to 0) the eloqdb6 uses the faster async write strategy which performs fewer disk writes but could lead to a damaged database environment in case of a system failure. The default value is 1.

With the previous HP Eloquence versions the write mode was specified using the dbvolchange command line utility (dsync, lsync flags). Specifying this setting in the server configuration make this important option more accessible.

HTTPUser = "user name"

The eloqdb6 server is able to display status information by supporting the HTTP protocol (you can use Netscape to monitor the database server process). If set, the eloqdb6 HTTP status display will require a matching user name (HTTP basic authentification) before allowing access to the eloqdb6 HTTP status. The default value is empty.

HTTPPswd = "pswd"

If set, the eloqdb6 HTTP status display will require a matching password (HTTP basic authentification) before allowing access to the eloqdb6 HTTP status. The default value is empty.

Please note: Unless the eloqdb6.cfg file is secured against access from ordinary users this is not secure. Please don't use a password which gains access to administrative accounts on the system as users could use it to get unauthorized access to the system. Since the HTTP status display only provides read-only access to the database status and poses a very limited security risk it might not worth the trouble.

HTTPFrame = {0|1}

If set, no link information is output on the HTTP status display. So the status page could be used in a web frame. Default value is 0.

This setting was defined in the [config] section in previous versions.

[config] section

IOThreads = number of threads

This specifies the number of I/O threads which are used by eloqdb6. eloqdb6 uses either separate processes or kernel threads to perform overlapped I/O operations. Please note that the eloqdb6 I/O threads are visible with the ps command. Default value is 4. A zero value disables usage of IO threads.
This configuration setting only effects the UNIX platform. On Windows NT, the overlapped I/O is provided by the operating system.

AllowSecondaryBlockingLock = {0|1}

If set, secondary blocking locks are allowed. Normally, secondary locks in a blocking mode (odd modes) will fail with database status -135 ("Second lock is not allowed in modes 1,3,5,11,13 and 15.") instead of blocking. Enabling this setting could result in a deadlock in the eloqdb6 server when programs use an incompatible lock strategy. Previous HP Eloquence versions disallow secondary blocking locks. Default value is 0.

VnodeCache

This configuration item is obsolete. The value is now adjusted dynamically by the eloqdb6 server. The item is still accepted to allow backward compatibility.

VbufElements

This configuration item is obsolete. The value is now adjusted dynamically by the eloqdb6 server. The item is still accepted to allow backward compatibility.

HTTPFrame

This setting has been moved to the [server] section. In the [config] section, it is still accepted to allow backward compatibility.

SyncerMinFree

This configuration item is obsolete. The syncer thread now uses a modified strategy where this parameter is not used anymore. The item is still accepted to allow backward compatibility.

SyncerNFlush

This configuration item is obsolete. The syncer thread now uses a modified strategy where this parameter is not used anymore. The item is still accepted to allow backward compatibility.

[devices] section

This section defines the "server devices" which can be used with dbstore and dbrestore. Each entry consists of the device name and an associated path.

A "server device" could either be a single file, a directory or a device. When no server devices are configured, dbstore and dbrestore operation is refused by the server.

The example below defines two server devices. The device "tape" points to a tape device file, the device "backup" points to a directory which is intended to hold the backup files.

 [devices]
 Tape = /dev/rmt/c1t0d0BEST
 Backup = /data/backup

Please refer to the Database Backup document for more information on server devices.

HTTP Performance monitor

A performance page has been added to the eloqdb6 HTTP status display which provides information on the server load and disk activities. Status values are available for the last ten minutes and an overall value since server start (example).

The following information is present:

server load: What percentage of time was spent serving requests vs. waiting on new requests. A low server load indicates that the server is waiting for the clients most of the time.
client requests: Number of client requests per second.
committed transactions: Number of committed transactions per second.
disk read requests: Number of disk read requests per second.
disk write requests: Number of disk write requests per second.
disk sync requests: Number of disk sync requests per second.

In addition, the statistics HTTP status page has been enhanced to include disk performance information (avg. time per disk access) and the on the percentage of overlapped vs. non-overlapped disk accesses (example).

On-line backup

The HP Eloquence A.06.20 database supports on-line backup. A backup can be made while the database is active. Clients can access and modify the database (at reduced performance). Previous HP Eloquence A.06.xx versions required that the eloqdb6 server was terminated.

The on-line backup is initiated with the dbctl backup start command which causes the eloqdb6 process to enter on-line backup mode. In on-line backup mode, no changes are made to the data volume(s) and an arbitrary backup tool could be used to backup the data volume(s). All changes are temporarily saved in the log volume(s) and are copied to the data volume(s) once the on-line backup mode has been finished with the dbctl backup stop command.

A detailed description how to backup your HP Eloquence database is available in the Database backup document.

dbctl command line interface to eloqdb6

dbctl is a new tool which allows access to a running eloqdb6 process. It can be used to retrieve eloqdb6 status information (which could be used in a script) or to manage some aspects of the eloqdb6 process (eg. shut down the server or control the on-line backup).

The eloqdb6 HTTP status display provides a more convenient interface to the eloqdb6 server status, but is harder to use from a script file. The dbctl utility intends to fill that gap and provides a convenient interface to text based tools.

For more information, please refer to the Database on-line utilities document.