Managing Caché

Caché System Administration Guide

Managing Caché

InterSystems: The power behind what matters

Caché System Administration > Caché System Administration Guide > Managing Caché

This chapter explains common Caché operations tasks including displaying process details, broadcasting messages, and monitoring processes. This chapter discusses the following topics:

Maintaining Local Databases

You can review and maintain local databases on the Databases page of the management portal, which you can reach by selecting Systems Operations and then Databases. For each local database, you see the following information:

Local Databases List Information

Column Heading	Definition
Name	The database name; click this name to display more details about this database.
Directory	The system directory in which the database resides.
Max Size (GB)	The maximum size allocated to which the database can grow, in gigabytes.
Size (MB)	The current allocated size of the database, in megabytes.
Status	The status of the database: mounted (including which permissions it has), unmounted, or dismounted. A mounted database is one that is required for Caché to start (that is, Mount Required at Startup is set to Yes), as described in Edit Database Properties in the “Configuring Caché” chapter of this guide; in this case, it is always mounted and accessible when Caché starts. Alternatively, it is a previously unmounted database that has been mounted dynamically when you accessed it or explicitly mounted it; in this case, it remains mounted until you explicitly dismount it or restart/stop Caché. An unmounted database is one that is not required for Caché to start (that is, Mount Required at Startup is set to No) and has been neither accessed nor explicitly mounted; it is mounted dynamically when you access it or explicitly mount it, and remains mounted until you explicitly dismount it or restart/stop Caché. A dismounted database is one that has been explicitly dismounted; it inaccessible until you explicitly mount it or restart/stop Caché (that is, a dismounted database is not mounted dynamically if you try to access it). To permanently dismount a database you must remove it from the configuration, as described in Local Databases in the “Configuring Caché” chapter of this guide. For information about explicitly mounting or dismounting a database, see the Dismount / Mount action buttons in this table.
Encrypted	Indicates whether or not the database is encrypted.
Journal	Indicates whether globals in the database are journaled with a Y or an N.
Dismount / Mount	Buttons that let you explicitly dismount or mount a database. The new status remains in effect until you explicitly change it or restart/stop Caché; to permanently dismount a database, you must remove it from the configuration.

In addition, the page contains a filter bar that you can use to control the number of databases displayed. For example, to list only the system databases, you might enter cac* in the Filter: text box; and/or to list only five databases per page, enter 5 in the Page size: text box; and/or to limit the number of rows displayed to three, enter 3 in the Max rows: text box (a + sign displayed with the number in the Results field indicates there are additional databases that meet the specified criteria, but they are not displayed).

Displaying Free Space Information

To get free space information, you can display the Database Freespace page of the Management Portal or use the ^%FREECNT utility.

Remember that the size and free space attributes of a database in normal operation change continuously, and that numbers reported by the portal or the utility at a given point in time are approximations only.

Display Free Space Information Using the Management Portal

To display the Database Freespace page, which shows information about the amount of free space on each local database and lets you compact and/or truncate databases, navigate to the Databases page and and click Freespace. The following table describes the information displayed on the Database Freespace page:

Local Databases Freespace Information

Column Heading	Definition
Name	The database name.
Directory	The system directory in which the primary volume of the database resides.
Max Size	The maximum allocated size to which the database can grow, in gigabytes. The default is unlimited when you create a database.
Size	The current allocated size of the database, in megabytes.
Expansion Size	Size (in MB) by which to expand the database. The default and recommended setting is zero (0) when you create a database, which indicates the use of system defaults (12% of the current size or 10 MB, whichever is larger). Under this setting, the expansion size will not be greater than 1GB.
Available	The amount of free space (in MB) available in the database.
% Free	The percentage of free space available in the database.
Disk Free Space	The amount of space free on the volume.
Status	The status of the directory, which indicates if the database is mounted and with what permissions.

Managing the free space (empty blocks) in a database is an important aspect of database maintenance. You can perform the following free space management operations on the Database Freespace page

Compact a database — Move free space distributed throughout a database to its end
Truncate a database — Return free space at the end of a database to the underlying file system

In addition, you can use the ^DATABASE utility for the following database management operations involving global blocks (blocks containing global data):

Compact globals in a database — Reduce unused space within global blocks and the overall number of global blocks, increasing free space
Defragment globals in a database — Relocate global blocks so that the blocks representing a given global are in continuous sequence

The ^DATABASE utility can also be used to display free space information and to compact and truncate databases, along with performing other database tasks such as recreating a database, which lets you clear the data in an existing database without changing the database’s name or size. See ^DATABASE in the “Using Character-based Security Management Routines” chapter of the Caché Security Administration Guide for information about the utility.

Note:

The data structures used by Caché are self-balancing and suffer no performance degradation over time. It is never necessary to take a database down to rebuild it nor to compress data or indices to regain performance.

Display Free Space Information Using ^%FREECNT

Caché also provides the ^%FREECNT utility, which you run by entering do ^%FREECNT in Terminal, to display the free space available in a database.

When using ^%FREECNT in the %SYS namespace, you can choose to display the free space of all databases by entering an asterisk (*) at the prompt, or enter one database directory name. For example:

%SYS>do ^%FREECNT
 
Database directory to show free space for (*=All)? *
 
Databases Selected
------------------
c:\MyCache\mgr\
c:\MyCache\mgr\cacheaudit\
c:\MyCache\mgr\cachelib\
c:\MyCache\mgr\cache\
c:\MyCache\mgr\cachetemp\
c:\MyCache\mgr\docbook\
c:\MyCache\mgr\samples\
c:\MyCache\mgr\user\
Device:
Right margin: 80 =>
 
 
                           Cache Database Free Space
                              Feb 15 2012  7:25 PM
Database                           Max Size  Size    Available %Free   Disk Free
c:\MyCache\mgr\                    Unlimited 191MB   19MB      9.94    60.79GB
c:\MyCache\mgr\cacheaudit\         Unlimited 1MB     0.43MB    43      60.79GB
c:\MyCache\mgr\cachelib\           Unlimited 319MB   27MB      8.46    60.79GB
c:\MyCache\mgr\cache\              Unlimited 1MB     0.55MB    55      60.79GB
c:\MyCache\mgr\cachetemp\          Unlimited 4MB     1.5MB     37.5    60.79GB
c:\MyCache\mgr\docbook\            Unlimited 144MB   11MB      7.63    60.79GB
c:\MyCache\mgr\samples\            Unlimited 114MB   52MB      45.61   60.79GB
c:\MyCache\mgr\user\               Unlimited 1MB     0.43MB    43      60.79GB

In a namespace other than %SYS, the utility shows the free space of the databases in that namespace. For example:

USER>Do ^%FREECNT
 
 
Databases Selected
------------------
c:\MyCache\mgr\user\
Device:
Right margin: 80 =>
 
 
                           Cache Database Free Space
                              Feb 15 2012  7:28 PM
Database                           Max Size  Size    Available %Free   Disk Free
c:\MyCache\mgr\user\               Unlimited 1MB     0.52MB    52      42.72GB

Note:

A <- flag (in the %Free column) indicates that the percentage of free space in the specified database has dropped below 5%. Ensure that there is enough space on the filesystem to handle database expansion.

You may choose the device to which to send the information and choose the line length of the display.

Compacting a Database

Compacting a database moves free space distributed throughout the database to its end by relocating global blocks. You can then return the free space to the underlying file system by truncating the database. (You can also compact globals; see Compact Globals in a Database.)

When you compact a database, you specify the amount of the available free space to be positioned at its end, and the operation moves enough global blocks from the end to the beginning to ensure that at least that amount of free space is located at the end. (The operation cannot create more free space, so it can never place more at the end than the total available amount.)

For example, suppose the size of a database is 50 MB, with 15 MB of that being free space, and 5 MB of that free space already positioned at the end of the database. If you compact the database and specify more than 5 MB but less than 15MB, global blocks are moved from the end of the database to the beginning until the free space at the end equals the amount you specified; if you specify 15 MB, all possible global blocks are moved to the beginning.

To compact a database:

Navigate to the Databases page (System Operations > Databases) and click Freespace to display the Database Freespace page.
Click Compact in the row of the database you want to compact. This displays the Compact Database page, which shows the name and location of the database, its current size, the total available free space, and the amount of free space currently at the end of the file.

Note:
If a database is mounted read only and the Caché instance is not a backup or async mirror member (see the “Mirroring” chapter of the Caché High Availability Guide), the Compact link does not appear in its row on the Database Freespace page.
The Target freespace (in MB) at end of file prompt allows you to specify the amount of free space you want at the end of the file following the operation. Your entry must be within the stated range. Once you have entered an amount, click OK. (If all of the free space is already at the end, or there is no free space, the prompt does not appear and the OK button is disabled.)

Note:
For a number of reasons, the operation may move more free space than the amount you specify. Conversely, because the numbers reported are approximations, it is possible that not all of the free space displayed can actually be moved.
When the Compact dialog box displays a message that the background job has started, click the Click here to view the background tasks page link near the top of the page to view the status of Compact Database Space background tasks on the Background Tasks page (System Operation > Background Tasks).
In the Compact dialog box, click Done to redisplay the Database Freespace page. If >> is displayed in the first column of the database row, refresh the page to see the new size displayed in the Size column.

Note:

The compact database operation is designed to run concurrently with normal database activity. The operation does consume some system resources, however, and may not complete if the system is under extremely high load. For these reasons, InterSystems recommends running this and other database reorganization operations (including compacting and defragmenting globals) during off-peak hours, and running only one such operation on a system at a time.

Truncating a Database

Truncating a database returns free space from the end of the database to the underlying file system. A database is often truncated after being compacted, which moves free space to the end of the database.

When you truncate a database, you specify a target size for the database. If there is sufficient free space at the end of database, the operation removes enough to reduce the database to the target size; if not, it removes all that can be removed. (To find out how much of a database’s free space is positioned at the end, compact the database; you do not need to complete the operation to display current total available free space and the amount at the end.)

Note:

This feature is not applicable to databases with raw volumes or cluster-mounted volumes.

To truncate a database:

Navigate to the Databases page (System Operation > Databases) and click Freespace to display the Database Freespace page.

Note:
Free space for truncation purposes is different than free space for storing data. Certain control structures can be deleted during truncation if they are not being used for data storage. This can lead to a difference in reported free space.
Click Truncate in the row of the database you want to truncate. This displays the Truncate Database page (System Operation > Databases > Freespace > Truncate), which shows the name, location, and current size in megabytes (MB) of the selected database.

Note:
If a database is mounted read only and the Caché instance is not a backup or async mirror member (see the “Mirroring” chapter of the Caché High Availability Guide), the Truncate link does not appear in its row on the Database Freespace page.
Enter the Target File Size (MB), which must be less than the current size, and click OK. Enter 0 to remove all possible free space from the end of the file.
When the page displays a message that the background job has started, click the Click here to view the background tasks page link near the top of the page to view the status of background tasks on the Background Tasks page (System Operation > Background Tasks).
In the Truncate dialog box, click Done to redisplay the Database Freespace page. If >> is displayed in the first column of the database row, refresh the page to see the new size displayed in the Size column.

Compacting Globals in a Database

The Compact globals in a database option of the ^DATABASE routine consolidates global data into fewer blocks, increasing the amount of free space in a database.

When globals are created and updated, Caché typically allocates data in a manner that fills global blocks to about 70% of capacity. (Globals that have grown entirely in collation order may be allocated at closer to 90%.) In general, allowing Caché to manage global block density automatically is sufficient. However, some nonsequential patterns of data deletion may reduce average global block density considerably.

Note:

To see the current density of the global blocks in a database on a global by global basis, you can run an integrity check (as described in Verifying Structural Integrity in the chapter “Introduction to Data Integrity” in the Caché Data Integrity Guide) and examine the Data Level output for each global.

When you compact globals, you specify a desired global block density (90% by default) and the operation attempts to come as close to this as possible by consolidating data—for example, rearranging global data that is spread across three blocks into two. Typically (but not always), compacting globals yields a meaningful increase in available free space within a database. (If you specify a target density that is lower than the current global block density of the database, the size of the database does not increase.)

To compact the globals in a database, use the following procedure:

Open Terminal and change to the %SYS namespace.
Enter do ^DATABASE and select 7) Compact globals in a database from the menu.
Specify the directory of the database on which you want to run the operation. You can specify multiple databases by entering ? at the Database directories to compact? prompt for a numbered list, and then a list of numbers, for example 1,4,7-10.
Indicate that you want to compact all globals, or instead enter a list of individual globals to be compacted.
Specify the target average global block density, indicate whether you want to display the results of the compacting operation for each global, specify the output device, and confirm.

Note:

The compact globals operation is designed to run concurrently with normal database activity. The operation does consume some system resources, however, and may not complete if the system is under extremely high load. For these reasons, InterSystems recommends running this and other database reorganization operations (including compacting a database and defragmenting globals) during off-peak hours, and running only one such operation on a system at a time.

Global compaction can involve a temporary increase in the size of the database being compacted. If this causes the database to reach its configured maximum size (see Local Databases in the “Configuring Caché” chapter of this guide), or if expansion is not possible because there is insufficient space available on the storage volume, the operation is canceled.

Defragmenting Globals in a Database

The Defragment globals in a database option of the ^DATABASE routine rearranges global blocks within the database so that all of the blocks containing data for a given global are in consecutive sequence. The operation does not place big string blocks or pointer blocks from a global in sequence, but it does locate them in a contiguous area. As part of the process, the Defragment globals in a database option compacts all globals in the same manner as the Compact globals in a database option, but with a target density of 70%. (If this is lower than the current global block density of the database, the size of the database does not increase.)

Note:

The CACHETEMP database cannot be defragmented.

In general, it is not necessary to run defragmentation on any regular basis. Some workloads, however, particularly those that read large portions of a database sequentially, can benefit from having global blocks organized sequentially.

The defragmentation process requires a certain amount of free space at the end of the database. For this reason, the following possibilities exist:

If there is enough free space at the end to perform the operation, it completes without any changes to the database beyond global defragmentation.
If there is not enough free space in the database, the database is expanded as necessary. When defragmentation is complete, you can truncate the database to remove the added free space.

If there is not enough free space in the database but there is significant free space that could be moved to the end, you are informed of this so you can first compact the database and then choose the Defragment globals in a database option again, reducing the amount of expansion required to complete the defragmentation operation..

To defragment the globals in a database, use the following procedure:

Open Terminal and change to the %SYS% namespace.
Enter do ^DATABASE and select 14) Defragment globals in a database from the menu.
Specify the directory of the database on which you want to run the operation.
Indicate that want to allow expansion, if required, and complete.

Note:

The defragment globals operation is designed to run concurrently with normal database activity. The operation does consume some system resources, however, and may not complete if the system is under extremely high load. For these reasons, InterSystems recommends running this and other database reorganization operations (including compacting a database and compacting globals) during off-peak hours, and running only one such operation on a system at a time.

Global defragmentation can involve a temporary increase in the size of the database being compacted. If this causes the database to reach its configured maximum size (see Local Databases in the “Configuring Caché” chapter of this guide), or if expansion is not possible because there is insufficient space available on the storage volume, the operation is canceled.

Important:

The defragment globals operation temporarily relocates all of the data in the database, regardless of the degree of global fragmentation in the database before the operation is run. Subsequent runs of the operation consume similar amounts of resources but do not provide any additional benefit.

Controlling Caché Processes

A Caché system runs a number of processes. Application code as well as Caché system code executes within these processes. There are three categories of Caché processes:

User processes, created when a user connects to Caché.
Background processes, created when a user issues an ObjectScript Job command, or by the Management Portal or a utility (see Using the Background Tasks Page).
Caché system processes.

In this chapter, the word “process” by itself refers to both user and background processes.

You can manage and control processes using the Management Portal:

Process Management Functions

Function	How to access function from the portal
Display process information	Display the Processes page (System Operation > Processes).
Display process details	Display the Processes page, then click Details in the right hand column of the selected process to display the Process Details page.
Suspend/resume a process	Display the Processes page, then click Details in the right hand column of the selected process to display Process Details page. Then click Suspend or Resume on the operations bar, as desired.
Terminate a process	Display the Processes page, then click Details in the right hand column of the selected process to display the Process Details page. Then click Terminate or Terminate with <RESJOB> Error on the operations bar, as desired.
Display process variables	Display the Processes page, then click Details in the right hand column of the selected process to display the Process Details page. Then click the Variables tab to display the process variables.
Broadcast messages to terminals	Display the Processes page and click the Broadcast button to open the Broadcast dialog.
Manage process refresh interval	Display the Processes page; optionally, click Details in the right hand column to display the Process Details page. In either case, edit the Refresh options (on the operations bar), as desired.

Display Process Information

To display all the active processes on the system and basic information about each, navigate to the Processes page (System Operation > Processes), which displays a table of the processes with statistics about each in columns.

The following table describes the process information available for display:

Process Column Information

Column Heading	Definition
Job #	Index of the Processes table.
Process ID	Operating system process identification number (PID).*
User	Name of the user who owns the process.
Device	Current device the process is using.
Namespace	Namespace in which the process is running.
Routine	Name of the routine that the process is currently executing.
Commands	Number of commands executed.
Globals	Number of global references, including updates, executed (database reads and writes) since the process entered Caché.
State	Process state. See the State property of the %SYS.ProcessQuery class documentation in the InterSystems Class Reference for an explanation of each state.
Client Name	Name of the client system that connected to, or initiated the connection to, the process.
Client EXE	Name of the executable that called the process.
Client IP	IP Address of the system that initiated the process.
O/S Username	Username assigned to the process by the operating system.
Details	Button appears if you have authority to maintain this process. See Display Process Details.

* An asterisk (*) appears next to the process id if the user entered Caché in programmer mode. A plus or minus sign appears next to Callin processes:

+ Process is in Caché
– Process is not in Caché

The Callin API is a Caché facility that lets you execute and evaluate ObjectScript commands and expressions from within C programs.

Display Process Details

The Process Details page displays detailed information about any process. To access this information from the Management Portal:

Display the Processes page (System Operation > Processes).
Click Details in the row of the appropriate process. (This option exists only on processes that you have authority to maintain.)
The portal displays the Process Details page for the process you selected.

Each category is described in one of the tables that follow:

In most cases, you can click any of the indicators to display a description of the item in the bottom detail box at the lower left corner of the page of the Process Details page.

General Information

Indicator	Definition
Process ID	Process ID (PID) number of this process.
User Name	Name of the user currently logged in for this process.
OS User Name	Username assigned to the process by the operating system.
Namespace	Namespace in which the process is executing.
Process Priority	Priority level of this process.
Global References	Number of global references made by this process.
Commands Executed	Number of commands executed by this process.
Memory Limit	Amount of memory (Kbytes) allocated for use by this process.
Memory Peak	Peak amount of memory (Kbytes) used by this process.
Private Global Blocks	Number of private global data blocks used by this process.
Current Device	Name of the I/O device currently in use by this process.
Memory Used	Amount of memory (Kbytes) currently in use by this process.
Open Devices	List of devices currently opened by this process.
Lock	Lock information for this process. Click the link at top of the detail box for additional details (mode, counts, and full reference).

Client Application Details

Indicator	Definition
Client Name	Node name of the client that is connected, or initiated the connection, to this process (if any).
EXE Name	Name of the executable client application client connected to this process (if any).
Client IP Address	IP address of the executable client application client connected to this process (if any).
Info	User-defined information (if any).

Execution Details

Indicator	Definition
Process State	Current execution state of this process.
In Tranaction	Indicates whether or not this process is currently within a transaction.
Last Global Reference	Last global referenced by this process.
Routine	Name of the routine this process is currently executing.
Source Location	Last reported source location (routine name plus offset) of this process.
Source Line	Last reported line of source code executed by this process, if available.

Stopping a Process

From this page you can also stop or resume a process. You can stop a process in one of the following ways:

Suspend a process with the intention of resuming the process later.
Terminate a process, which entirely cancels the process.

Suspend or Resume a Process

You may want to suspend a process if you are not sure what it is doing and want to investigate, or if a more important process is trying to run and needs the CPU cycles. To access this option from the Management Portal:

Display the Processes page (System Operation > Processes).
Click Details in the row of the appropriate process. This option only exists on processes that you have authority to maintain.
Click Suspend on the options bar.

You may resume a suspended process at any time by clicking Resume from the same page.

Terminate a Process

You may want to terminate a process if it becomes unresponsive or is affecting other processes or users. To access this option from the Management Portal:

Display the Processes page (System Operation > Processes).
Click Details in the row of the appropriate process. (This option exists only on processes that you have authority to maintain. The portal displays the Process Details page for the process you selected.
Click Terminate on the options bar.

Optionally, to log the status of the process when it terminates, select the Terminate with RESJOB Error check box.

Note:
This option is enabled by default.
Click Yes to confirm that you want to terminate the process. There is no way to resume a terminated process.

Display Process Variables

The Process Variables page displays all the variables used in the selected process giving the global name and the value of the global. To access this information from the Management Portal:

Display the Processes page (System Operation > Processes) page.
Click Details in the row of the appropriate process. (This option exists only on processes that you have authority to maintain.) The portal displays the Process Details page for the process you selected.
Click Variables on the options bar.

Broadcast Messages to Terminals

You can broadcast messages to the terminals associated with a selected process or all processes; this utility is useful, for example, to ask people to sign off the system. However, you must use it carefully or you may cause messages to appear in the middle of reports that may be printing at the time.

The utility temporarily takes control of each terminal as it sends the message. Once the terminal receives the message, the previous process continues. The message appears on the terminal screen; it may disrupt the screen display, but it does not affect user input. The message does not appear in windows running Caché utilities.

To broadcast a message to the terminals associated with a selected process, do the following in the Management Portal:

Display the Processes page (System Operation > Processes).
Click Broadcast (on the options bar) to open the Broadcast window.
Enter the message to broadcast in the text box.

(The dialog box notifies you if there are no active processes that can accept a message; you do not see a message text box or list of processes. Click Close.)
Select the appropriate check boxes for the appropriate processes (PIDs) to receive the broadcast message. Use the Select All and Clear All buttons accordingly to help with the selection.
Click Broadcast.
After the completed message displays, click Close.

Manage Refresh Interval

You can control whether or not to auto-refresh the process information and, if you want to refresh the information, you can specify how frequently it is refreshed. The minimum interval for auto-refreshing the data is 5 seconds; the default interval is 10 seconds.

Note:

Auto-refresh is turned off by default; to refresh processes manually, click the refresh icon.

To turn on auto-refresh for all active processes, do the following in the Management Portal:

Display the Processes page (System Operation > Processes).
Click the on (on the options bar) and enter the interval (minimum: 5 seconds) in the text box.
To turn on auto-refresh for process details, do the following in the Management Portal:
1. Display the Processes page (System Operation > Processes).
2. Click Details in the row of the appropriate process. (This option exists only on processes that you have authority to maintain. The portal displays the Process Details page for the process you selected.
3. Click the on (on the options bar) and enter the interval (minimum: 5 seconds) in the text box.

Using the Task Manager

To use the Task Manager, select System Operation > Task Manager) to display the following menu options:

New Task (schedule a new task)
On-demand Task(execute a task on demand)
Upcoming Tasks (view tasks scheduled to run in the next 24 hours)
Task Schedule (view all scheduled tasks)
Task History (view completed tasks)
Import Tasks (import tasks previously exported to files, possibly by another Caché instance

Note:

The Task Manager polls every 60 seconds to see if there are any Tasks to be run. When you click Perform Action Now to schedule a Task, there may be a delay of up to 60 seconds before the newly scheduled Task actually runs.

New Task

The New Task option starts the Task Scheduler Wizard.

The first page of the wizard asks for the following information:
- Task name
- Description
- Namespace to run task in — choose from the list of defined namespaces in which to run the task
- Task type — choose from among the listed tasks (the list varies with the namespace you select at the previous prompt)
  
  Note:
  Depending on the task type selected, you may be presented with a form in which to specify additional information; for example, if you are scheduling an IntegrityCheck, the form prompts you for Directory, Filename, and KeepDays (number of days to keep the file).
  - CheckLogging — creates an alert or turns off ^%ISCLOG or ^ISCSOAP logging if it has been running too long (by default, 2 days)
  - CleanSQLIndex— cleans up stale SQL Statemne tIndex entries
  - CumuIncrDBList — a cumulative backup of databases in the defined list
  - DiagnosticReport — collects and delivers diagnostic reports to the WRC
  - FullAllDatabases — a full backup of all databases
  - FullDBList — a full backup of databases in the defined list
  - IncrementalDBList — an incremental backup of databases in the defined list
  - IntegrityCheck — an integrity check of databases in the namespace. The Integrity Check task only appears when the %SYS namespace is selected.
  - InventoryScan — compiles an inventory scan of the instance
  - PurgeAudit — purge the audit database after a specified time following a journal switch
  - PurgeBackupLog — purge the backup log after a specified time following a database backup
  - PurgeErrorsAndLogs — purge error globals and cconsole.log based on settings in the cache.cpf file (see ErrorPurge and MaxConsoleLogSize parameters in the Startup section of the “Introduction to the Caché Parameter File” chapter of the Caché Parameter File Reference)
    
    Note:
    When System Monitor is running, it monitors and limits the size of the console log.
  - PurgeJournal — purge journal files that meet the purging criteria
  - PurgeTaskHistory — purge task manager history files
  - RunLegacyTask — run a legacy task, that is, your own programmatic task; the line you enter in the text box, for example do ^MyCode, must be executable in Terminal
    
    Note:
    Do not use the local variable Status in RunLegacyTask code. Caché uses this variable, and if it is modified by RunLegacyTask code, the task is likely to end with an error status.
    
    A legacy task that fails to complete due to an error is marked Suspended due to error and is not scheduled to run until the error is corrected and you resume the task.
  - SecurityScan — disables expired user accounts, and expires user passwords and CSP session tokens
  - ShadowPurge — purge shadow files
  - SuspendOnError — determines what happens if the Task returns an error %Status from the OnTask() method. Errors encountered by the Task Manager trying to execute the task (login error or no such Task found) do not check this flag.
  - SwitchJournal — switch to a new journal file
  - UpdateSQLStats— updates the information on SQL query statistics
  Note:
  You can define your own task types using the %SYS.Task.Definition API; see the class documentation in the InterSystems Class Reference.
- Task priority — Choose from Priority Normal > Priority Low, or Priority High.
- Run task as this user — Choose from the list of defined users. To choose a different user than the one you are logged in as, you must have the %Admin_Secure:Use privilege.
  
  Note:
  Each task consumes a license unit, with the license user ID based on the Caché username you select; see License Login Special Considerations in the “Caché Licensing” chapter of this guide for more information.
- Open output file when task is running and Output file — If the task creates output, the log file is written to the directory specified.
- Suspend task on error? — Specify whether the task will be rescheduled and continue to run after an error, or suspended. The default is No, to reschedule and run the task after an error.
- Reschedule task after system restart? — Specify whether you want to reschedule the task when the system restarts (that is, if the system is down when the task is scheduled to run):
  - No specifies that the task should run when the system restarts.
  - Yes specifies that the task should be rescheduled for the next logical time after the system restarts.
- Send completion email notification to — If you have configured email settings for the Task Manager (see Configuring Task Manager Email Settings in the “Configuring Caché” chapter of this guide), enter a comma-separated list of email addresses to which a notification should be sent when the task ends successfully.
- Send error email notification to — If you have configured email settings for the Task Manager, enter a comma-separated list of email addresses to which a notification should be sent when the task ends in error.
- How should task run for Mirror — If this instance is a mirror member, specify the type of member the task can be run on:
  - run on primary failover member only
  - run on backup failover member and async members only (all except primary)
  - run on all mirror members (primary, backup, and asyncs)
  Note:
  When the status of a failover member is in transition, for example when the backup is in the process of taking over as primary, the Task Manager does not run any tasks on that member until its status as primary or backup is established.
Click Next to specify when you want the task to run.
Click Finish to schedule the task.

All tasks are configured to expire by default. To change this:

Open Terminal.
Enter zn “%SYS” to change to the %SYS namespace.
Enter do ^TASKMGR.
Select option 2.
Enter the task number you want to edit.
Press Enter to save the defaults of each option until you reach Task Expires?
Enter No.

The selected task will no longer expire.

There are three additional expiration fields that control when a task expires. These are controlled by days, hours, and minutes. To adjust when a specific task expires:

Open Terminal.
Enter zn “%SYS” to change to the %SYS namespace.
Enter do ^TASKMGR.
Select option 2.
Enter the task number you want to edit.
Press Enter to save the defaults of each option until you reach Expires in how many days?, Expires in how many hours?, or Expires in how many minutes?
To edit the expiration times of this task, enter the days, hour, or minutes you would like to schedule.

The values for this expiration are now saved.

For details on the information necessary to schedule or edit a task, see the %SYS.TaskSuper class documentation in the InterSystems Class Reference.

On-demand Task

The On-demand Task page (System Operation > Task Manager > On-demand Task) lists the tasks you have scheduled as on-demand. The list includes the task name, a description, and an option to Run the task from this page. You can sort the information in the table by clicking any column heading. When you click Run, the Run Task Wizard page displays the task name and ID, and the date and time the task will run; click Perform Action Now to confirm the information and schedule the task.

Upcoming Tasks

The Upcoming Tasks page (System Operation > Task Manager > Upcoming Tasks)lists the tasks scheduled to run within a certain interval. To select an interval, click an option in the Scheduled to run: search pane to the left of the task list. If you select the To a date option, you can either enter a date in yyyy-mm-dd format or click the calendar icon to select a date from the calendar.

You can sort the information in the task list by clicking any column heading. You can Suspend or Resume the scheduling of each task by clicking the appropriate option:

Suspend — Lets you suspend the task; a do you want to reschedule task when task is supposed to run? drop-down list lets you specify:
- No to suspend it indefinitely.
- Yes to suspend it now, and resume it when it is normally scheduled to run.
Resume — Lets you resume a suspended task.

Task Schedule

The Task Schedule page (System Operation > Task Manager > Task Schedule) lists all scheduled tasks. You can sort the information in the table by clicking any column heading. You can view Details or History, as well as Run, a scheduled task by clicking the appropriate option:

taskname — Lets you view details about the task and perform operations on it.
History — Displays the task’s history.
Run — Lets you run the task. A Run Task wizard displays the task name and ID, and the date and time the task will run; click Perform Action Now to confirm the information and schedule the task.

Task Details

To display detailed information about a scheduled task and perform one of several operations on it, click the task’s name in the Task Name column. The Task Details page displays information and execution details about the selected task. You can perform one of the following operations on the task by clicking the appropriate button:

Edit — Lets you change the task definition and schedule using the Task Scheduler Wizard.
History — Lets you view the task’s history.
Resume > Suspend— Let you suspend a task or resume a suspended task, as on the Upcoming Tasks page.
Delete — Lets you permanently delete the task.
Export — Lets you export a task to a file that can later be imported, including by another Caché instance.
Run — Lets you schedule the task. When you click Run, the Run Task Wizard page displays the task name and ID, and the date and time the task will run; click Perform Action Now to confirm the information and schedule the task.

Note:

Some of the actions options described are unavailable while a task is running.

Scheduled Task History

To display history information about an individual scheduled task, click the History link in the row of the item. The Task History page displays detailed history for the selected task. The Result column indicates the outcome the last time the task was run, showing either Success or an error message. You can sort the information in the table by clicking any column heading.

The Details link at the top of the page displays the Task Details page for the selected task.

Task History

The Task History page (System Operation > Task Manager > Task History) lists the history of all tasks executed by the Task Manager. You can sort the information in the table by clicking any column heading.

Import Tasks

The Import Tasks page (System Operation > Task Manager > Import Tasks) lets you import and run a task by browsing to a previously-exported task file, then clicking Perform Action Now. For information about exporting tasks to a file, see Task Details in this section.

Using the Background Tasks Page

A background task is an asynchronous job process that runs in the background, independently of the process that created it. A background task is created when a user issues an ObjectScript JOB command, or by the Management Portal or a utility to execute a job without requiring the user to wait for completion. For example, when you use the portal to truncate a database, as described in Truncating a Database earlier in this chapter, a background task is started.

The Background Tasks page (System Operation > Background Tasks) lists past and active background tasks. You can purge the log of past background tasks at any time.

When a background task is active, the process can also be seen on the Processes page (System Operation > Processes), as described in Controlling Caché Processes.