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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
Administrator's ReferenceThe includes comprehensive descriptions of HCL Informix® configuration parameters, the system-monitoring interface (SMI) tables in the sysmaster database, the syntax of database server utilities such as onmode and onstat, logical-log records, disk structures, event alarms, and unnumbered error messages.
Administrative Utilities
The onstat utilityThe onstat utility reads shared-memory structures and provides statistics about the database server at the time that the command runs.
onstat -g monitoring optionsThe options that you can use with onstat -g command are used for support and debugging only. You can include only one of these options in the onstat -g command.
onstat -g rah command: Print read-ahead request statisticsUse the onstat -g rah command to display information about read-ahead requests.
onstat -g rah command: Section 1 Read AheadThis section displays general cumulative information about read aheads instance-wide.

onstat -g rah command: Section 1 Read Ahead

This section displays general cumulative information about read aheads instance-wide.

Figure 1. onstat -g rah command output, section 1
Read Ahead
# Qs                     3
# RA Daemon Threads      3
# Requests               4445632
cur. queued              6
max. queued              10
max. indiv. Q len        3
# Continued              4667
# Memory Failures        0
Way Behind               0
Daemon Frees             0
Last Thread Add          10/31/2021.11:02:59

Output description

# Qs: Number of queues for read-ahead requests.
# RA Daemon Threads: Number of read-ahead daemon threads servicing the queues.
Requests: Number of read-ahead requests made in total.
cur. queued: Number of read-ahead requests currently in the queue(s) waiting for a daemon to process them.
max. queued: The maximum number of requests queued at a given moment.
max. indiv. Q len: The maximum number of requests in an individual queue.
# Continued: Number of times a read-ahead daemon continued processing a request rather than switch temporarily to another one. This occurs when the request processing is not ahead of the reader.
# Memory Failures: Number of failed requests because of insufficient memory.
Way behind: Number of page list requests that were dropped because the read-ahead daemon was too far behind.
Daemon Frees: Typically a reader will free its own read-ahead request structures, but occasionally a daemon must take on that job, for example if the reader has exited before the read-ahead request was completed.
Last Thread Add: Date and time when the last read-ahead thread was added.

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