IBM Informix Interview Questions and Answers [ STEP-IN ]

Last updated on 18th Nov 2021, Blog, Interview Questions

Looking for the top IBM Informix interview questions to prepare for your interview. Go through some of the best IBM Informix interview questions with detailed answers before you get ahead. IBM Informix to become an Expert in IBM Informix and learn all the instructions required to install and configure the server. Therefore, IBM Informix professionals need to encounter interview questions on IBM Informix for different enterprise IBM Informix job roles. The following discussion offers an overview of different categories of interview questions related to IBM Informix to help aspiring enterprise IBM Informix Professionals.

1. Is Informix a good database?

Ans:

Informix is ideal for situations where minimal database administration efforts are required. It is generally considered to provide stable uptime as well as high transaction throughput. It also provides data type extensions which are not included in the basic SQL specification.

2. What is a chunk in Informix?

Ans:

A chunk is a physical portion of the disk on which the Informix stores its data. A fragment can be a raw partition or a file system file.

3. What database does IBM use?

Ans:

DB2 is a database product from IBM. It is a Relational Database Management System (RDBMS). DB2 is designed to store, analyze and retrieve the data efficiently. DB2 product is extended with the support of Object-Oriented features and non-relational structures with XML.

4. What is a Database Object in IBM Informix?

Ans:

The Database object is a table or a view or any other type of objects supported by Informix. The Database objects are created using a statement SQL CREATE for these types of objects, and the database objects have owners.

[database[@server_name]:][owner.]object

5. Who Conceived And Designed The Informix Database Management System?

Ans:

Conceived	Informix
The Informix database management system was conceived and designed by Roger Sippl in the late 1970s.	Informix was founded in 1980, went public in 1986, and for a period during the 1990s Informix was the second most popular database system, after Oracle.

6. What is the role of Binary Large Objects in Informix?

Ans:

A large binary object which is also known as a Blob is a collection of the binary data which is stored as a single entity in a database management system. Blobs are the audio or the images or the other multimedia objects.

7. What is NoSQL database?

Ans:

NoSQL, also referred to as “not only SQL”, “non-SQL”, is an approach to database design that enables the storage and querying of data outside the traditional structures found in relational databases.

8. Where are ODBC Drivers located?

Ans:

The 32-bit version of the Odbcad32.exe file is located in the %systemdrive%\Windows\SysWoW64 folder. The 64-bit version of the Odbcad32.exe file is located in the %systemdrive%\Windows\System32 folder.

9. Is Db2 A Rdbms?

Ans:

IBM Db2 is a family of data management products, including database servers, developed by IBM. It is a Relational Database Management System (RDBMS) which supports object-oriented features and non relational structure with XML. Db2 is designed to store, analyze and retrieve the data efficiently.

10. What are IBM Informix components?

Ans:

11. How is SQL used in DB2?

Ans:

The language that you use to access the data in Db2 tables is the structured query language (SQL). You can issue SQL statements to accomplish the following actions: Define, modify, or drop data objects, such as tables. Retrieve, insert, update, or delete data in tables.

12. What is error in DB2?

Ans:

An important feature of DB2 programs is the error processing. The error diagnostic containing the SQL Return Code is held in the field SQLCODE within the DB2 SQLCA block. SQLCODE is no longer part of the SQL-standard. The SQL-standard replaced SQLCODE by the more detailed SQLSTATE.

13. What Is A Binary Large Object ?

Ans:

Any object for whom its binary data file can be stored and restored with success into a database can be considered a BLOB.

As an example, an ecommerce site can store the product photos and videos inside a database. But that’s not a best practice.

14. What Are The Options/Commands Used Which Dbspace A Database Resides?

Ans:

The DBA can use:

The onmonitor utility

oncheck -pe | egrep “DBspace Usage Report|” | more

A query joining sysdbspaces and sysdatabases tables located in the sysmaster database

15. Why Do Foreground Writes Decrease Performance ?

Ans:

Whenever the Informix sqlexec process searches for a free / clear buffer in order to read a page from the disk into that buffer it is called foreground write operation. The performance penalty appears when there are no free / clean buffers left, and sqlexec has to search for a less used buffer, write its content to disk, clean the buffer and reuse the buffer for a foreground write operation – having the disadvantage of NOT being asynchronous (as chunk writes/lru writes)

16. What is cursor in Db2?

Ans:

Db2 has a mechanism called a cursor. In Db2, an application program uses a cursor to point to one or more rows in a set of rows that are retrieved from a table. You can also use a cursor to retrieve rows from a result set that is returned by a stored procedure.

17. Explain The Concept Of Fragment Elimination In Informix ?

Ans:

Fragment elimination appears when the following conditions are all satisfied:

• A table is fragmented
• The fragmentation formula doesn’t create overlapping ? asta oricum nu e permis (overlapping)
• A query uses equality filter on a column used in the fragmentation formula
• If the above conditions are met, the Informix engine can skip fragments (data is not searched there) that don’t comply with the query filter

18. What Are The Sql Joins Available In Informix?

Ans:

INNER JOIN, LEFT / RIGHT OUTER JOIN, FULL OUTER JOIN, CROSS JOIN

19. What Command Would You Use To Move The Physical Log?

Ans:

• onparams -p -s -d -y
• onmonitor utility

in newer IDS versions, use the SQL API to alter the plog location

20. What is IBM Informix SNMP architecture on UNIX?

Ans:

21. What Are The Informix Isolation Levels And Can You Explain Each One ?

Ans:

DIRTY READ: Reads the data without checking if it’s committed or not. No locks are held during the read

COMMITTED READ: Read only the committed data. No locks held

REPEATABLE READ: Reads only the committed data. A shared lock is held on the rows. Other sessions can obtain shared locks on those rows, but no one can get an exclusive lock.

CURSOR STABILITY

Ans:

22. An Index Is Reaching A Limitation On The Number Of Pages It Has, Can You Explain Why This Limitation Exists And What Work You Would Do To Get Around It?

Ans:

• A dbspace can have one or more partitions. Each partition has a special “header” info in the first extent.
• The partition header keeps a list of the partition’s extents. If the object holding the space in the partition (table / index) has a great number of extents, the header may not be able to keep the full list.
• Workarounds:
• increase first / next extent size and recreate the object
• change the page size -> will result in a lower number of extents
• recreate the index in a dbspace having a larger page size

23. How Would You Check That A Given Index Is Consistent And Has No Corruption? If Corruption Occurred On A Database What Would Your Process Be?

Ans:

Index (along with database and table) consistency can be verified with oncheck -cDI database_name:table_name. Preferably with the instance put in quiescent mode. If just the index is corrupted (and not fixable by oncheck), an option will be to recreate the index.

24. Why Is Update Statistics Important To A Database?

Ans:

Running update statistics will update the system catalog information about the database.

This information is used by the Informix optimizer to calculate costs and execution plans for day to day queries. Lack of up-to-date information about data distributions may result in severely bad plans.

25. Explain The Purpose Of Optimizer Directives And How/why You Would Use Them

Ans:

A DBA can use directives mostly to change / test / evaluate the execution plan (costs / benefits) for a query, by forcing an index / change join order / etc.

26. And Why Are These Important?

Ans:

• Monitor impact on system’s CPU:
• Instance sys vcpu + Instance user vcpu
• Locks requests / waits
• Active locks
• Monitor impact on system’s storage (IO) / memory:
• Buffer reads / writes / waits
• Page reads / writes /
• Disk reads / writes
• Logical contention:
• lock requests / waits
• deadlocks
• eventually rollbacks
• Monitor instance health & status
• Dbspaces total / used / free space
• Checkpoint intervals & duration
• Sequential scans number
• Number of not yet backup-ed logical logs
• Number of active sessions
• And of course the instance online log.

27. Is Informix same as DB2?

Ans:

Informix is often compared to IBM’s other major database product, DB2, which is offered on the mainframe zSeries platform as well as on Windows, Unix and Linux. … Informix is generally considered to be optimized for environments with very low or no database administration, including use as an embedded database.

28. Can You Explain Pdq Priority?

Ans:

By setting PDQ PRIORITY the DBA can change the query execution priority and increase the number of internal threads spawned by Informix to satisfy the query. Also, some memory allocation strategies differ upon setting PDQPRIORITY.

29. How Could You Increase The Speed Of Ontape/onbar Backups?

Ans:

• On a platform with fast cpus, write low performance and compressible data, the ontape output may be piped and compressed before getting on disk (less IO write operations).
• With onbar, greater backup speeds can be achieved by:
• Increase the number of onbar threads -> BAR_MAX_BACKUP
• Increase the buffers used by onbar (if memory is available) ? BAR_NB_XPORT_COUNT
• Use a fast storage for the storage pool (We use onbar + IBM Tivoli Storage Manager)
• Consider taking incremental backups

30. What is Informix HQ?

Ans:

31. Explain Checkpoints And Why In 9.4 They Were Better Than In Previous Versions Of The Engine?

Ans:

You are still using 9.4 ? It’s been out of support for 3 years … . We upgraded from 10.00FC6 to 11.50FC7 last year.

The first Informix database I started to administrate was IDS 10.00FC4. So my best guess is that 9.4 introduced partially non-blocking checkpoints (fuzzy checkpoints ?), these being superseded in the latter versions.

The checkpoint is the moment when Informix will flush the contents from the bufferpool to disks.

32. How Would You Convert A Secondary Server Into A Primary Server ?

Ans:

EXECUTE FUNCTION task(“ha sds primary”,”srv_slave”);

If it is HDR and the secondary becomes the new standalone server: onmode -d standard

33. Why A Foreground Write In Informix Decrease Performance?state The Reason For The Same?

Ans:

Foreground writes (FG) should always be zero. A foreground write is caused when a session needs to have a page from disk placed into the buffer pool, but there are no clean/free buffers available. In this case, the sqlexec thread will pick a page off the least recently used side of an LRU queue, write it out, and mark the page as clean. This process is time consuming for a session and should be avoided.

34. What Is The Size Of Informix Page?

Ans:

The most common page size used is 2KB, though some systems use 4KB pages.

35. What Is Informix Universal Server?

Ans:

Informix Universal Server was the brand name given to the 9.X versions of the product; the upgrade from the Informix Dynamic Server (IDS) 7.X products, skipping the XPS 8.X release numbers. The 9.X server contained a number of functional advances (data type extensibility, DataBlades etc), as well as improvements to the storage manager and SQL processing. The most recent versions of the Informix line — 10.X — are an evolutionary progression over the 9.X engine.

36. What Can Be Used To Capture An Isam Error From An Informix Odbc Program On Unix?

Ans:

We can use the SQLCA structure to get the ISAM Error.

sqlca.sqlerrd[1] holds the ISAM error return code.

We can also use the target lmsg() and getmsg() library functions to obtain ISAM error message text.

37. Somehow Informix Fails To Go Online. Is There A Way To View What Oninit Is Doing?

Ans:

Yes, you can start Informix in verbose mode:

• oninit -v (this works on NT as well)
• Informix will print everything that happens.
• To close the verbose mode: start a second terminal session (UNIX) or command prompt (NT) and execute:
• onmode -ky

N.B. Don’t close your terminal session (UNIX) or command prompt (NT) while in verbose mode. This will take Informix offline immediately.

38. I Think I Screwed Up My Onconfig File, And I Do Not Have A Backup Of It. What Should I Do?

Ans:

If Informix is still online, you can get a new onconfig with:

• onstat -c >onconfig
• If Informix is offline, you can retrieve the settings from the database with:
• oncheck -pR
• or
• oncheck -pP 1 1

39. Can I Install Informix On A Non-english Version Of Windows Nt?

Ans:

Yes, but you need to install version 7.30 TC 6 or higher.

40. What is ibm Informix dbspace?

Ans:

41. Can I Ask About Perl, Dbi And Dbd Informix? Other Products?

Ans:

You may ask questions about Perl, DBI and DBD::Informix, but only if an IBM or Informix database is involved, somehow — it is not a general forum for arbitrary questions about Perl. However, there are alternative forums that you should also use, described in the product.

42. Explain About the Light Scans In Informix?

Ans:

Light scans occur under the following conditions: The optimizer chooses a sequential scan of the table. The number of pages in the table is greater than the number of buffers in the buffer pool. The isolation level obtains no lock or a shared lock on the table: Dirty Read (including non logging databases) isolation level Repeatable Read isolation level if the table has a shared or exclusive lock Committed Read isolation if the table has a shared lock

43. What Is Informix Binary Large Object?

Ans:

A binary large object, also known as a blob, is a collection of binary data stored as a single entity in a database management system. Informix invented an alternative backronym, Binary Large Object. Blobs are typically images, audio or other multimedia objects, though sometimes binary executable code is stored as a blob.

44. What Is Extent In Informix?

Ans:

If a table is designed without specifying extent sizes, Informix uses a default of 16 pages for the first and 8 pages for each subsequent extent. Extent sizing is done when the table is initially created.

45. Mention The Database Server Operating Modes Available For Informix?

Ans:

Informix IDS provide following modes:-

Online mode: This is the normal operating mode of the database server.

Offline mode?: The database server is not running. Shared memory is not allocated.

Quiescent mode: This is the normal operating mode of the database server.

Administrators use this mode to perform maintenance functions that do not require the execution of SQL and DDL statements. Only the administrator (user Informix) can access the database server.

Single-User mode: This mode is an intermediary mode between Quiescent mode and Online mode.

Administrators use this mode to perform any maintenance task, including tasks requiring the execution of SQL and DDL statements. Administrators can also perform all other functions available in Online mode. You can see the current database server mode by executing the onstat – utility from the command.

46. Explain about light scans in Informix?

Ans:

Light scans occur under the following conditions: The optimizer chooses a sequential scan of the table. The number of pages in the table is greater than the number of buffers in the buffer pool. The isolation level obtains no lock or a shared lock on the table: Dirty Read (including non logging databases) isolation level Repeatable Read isolation level if the table has a shared or exclusive lock

47. Who uses Informix?

Ans:

IBM

The companies using IBM Informix are most often found in the United States and in the Computer Software industry. IBM Informix is most often used by companies with 50-200 employees and 1M-10M dollars in revenue.

48. What Is The Option Or Command Used In Informix For Finding Which Dbspace A Database Resides?

Ans:

from command line# onmonitor ->Logical-Logs->Databases.

49. What is difference between Oracle and Db2 database?

Ans:

Db2 is well known for reliability and scalability, while Oracle Database is more known for its wide range of applications, tools, skills, and partners available. Both are very stable databases, with large amounts of documentation and good support. You may also be considering other options, such as Db2 vs. SQL Server.

50. What is Informix RSS?

Ans:

51. Is IBM Db2 easy to use?

Ans:

IBM Db2 on Cloud is a solid offering that gets a 4.0 rating in this review for its sheer ease of use. Some developers chafe at the limitations in design control, though, especially when compared with the extreme flexibility of Editors’ Choice MongoDB Atlas in providing tons of controls for developers.

52. What Is Informix Instance?

Ans:

An Informix instance is a single connection to shared memory. It is represented by one or more init processes. When Informix is started or stopped, these processes appear and disappear. Informix used to use the term “server” when referring to an instance, hence the environment variable DBSERVERNAME.

53. Who uses IBM Db2?

Ans:

Companies using IBM Db2 for Data management software include: Audi AG, a Germany based Automotive organisation with 90783 employees and revenues of $67.60 billions, Mizuho Bank, Ltd, a Japan based Banking and Financial Services organisation with 59132 employees and revenues of $17.72 billions, Fawry, a Egypt based

54. What Rules Exist Regarding Format, Content, Flame Wars, Etc?

Ans:

None; this is a news group! That is, there are no rules enforced by the software. There are periodic discussions on c.d.i about what should and should not be said. This is my FAQ, so it gets my spin on the rules that should be followed.

Format: HTML postings are strongly discouraged; so are MIME postings. Both cause problems with many frequently used news readers. That means that attachments aren’t encouraged either. Also, sending the same information twice, once in HTML and once in plain text, is downright wasteful.

55. What Is The Informix-list@iiug.org Mailing List?

Ans:

The Informix-list@iiug.org mailing list is a bi-directional gateway to the comp.databases.Informix (c.d.i) UseNet news group. Messages posted to the news group are forwarded by mail to subscribers of the mailing list; responses sent to the Informix-list@iiug.org email address are also posted to the news group; and the gateway manages to keep track of things so that postings do not repeat themselves. The mailing list is ‘closed’ in that you cannot post directly to the list unless you also subscribe to the list. However, you can always post to the news group instead; that is fully open and unmoderated.

56. Is Informix open source?

Ans:

IBM Informix supports database access for client applications that are written in the Ruby programming language with two open source packages.

57. What are the advantages of IBM Db2?

Ans:

• Improved availability of data. DB2 data sharing helps you meet your service objective by improving availability during both planned and unplanned outages.
• Scalable growth.
• Flexible configurations.
• Protected investments in people and skills.

58. Is IBM Db2 SQL?

Ans:

The language that you use to access the data in Db2 tables is the structured query language (SQL). SQL is a standardized language for defining and manipulating data in a relational database.

59. What is Informix database server?

Ans:

IBM® Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.

60. What Current customer bi architecture with Informix?

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61. What is IBM Informix used for?

Ans:

IBM® Informix® is an embeddable, high-performance database for integrating SQL, NoSQL, JSON, time-series and spatial data. Designed for analytics on the edge, in the cloud or on premises, the low-footprint database features self-management and automated administrative capabilities.

62. Who developed Informix?

Ans:

Informix was created by Roger Sippl. In 1986, The company changed its name to Informix Corporation and went public, raising $9 million.

63. How do you use Informix?

Ans:

• Start OAT.
• Connect to the database server.
• Create a demonstration database.
• View information about the tables in the stores_demo database.
• View the health of the database server.
• Configure the database server by setting configuration parameters.
• View storage spaces.

64. What kind of database is Informix?

Ans:

Relational

IBM® Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.

65. What are the uses of key value locking in Informix?

Ans:

The database server uses a concept called key-value locking to lock the deleted row. When the database server deletes a row, key values in the indexes for the table are not removed immediately. Instead, each key value is marked as deleted, and a lock is placed on the key value. One of the most important uses for key-value locking is to assure that a unique key remains unique through the end of the transaction that deleted it.

66. What are the three components of an Informix database server?

Ans:

A web-based business intelligence solution with integrated reporting, analysis, scorecarding, and event management features.

67. What is Informix developer?

Ans:

IBM Informix Developer Edition is free database software for application development and prototyping. IBM® Informix® is a secure embeddable database, optimized for OLTP, IoT and is forging new frontiers with its unique ability to seamlessly integrate SQL, NoSQL/JSON, time series and spatial data.

68. How do I access my Informix database?

Ans:

Look for Informix command line icon, it’s a shortcut, but very specific to your instance configuration, this file will define the Informix environment variables (InformixSERVER, PATH, etc) and open the prompt to you. Then just type dbaccess and voila

69. How do I create an Informix database?

Ans:

• 1 Log on to the database server computer as user root.
• If your database server computer is not the same as your install computer, you must run ccm install -l.
• Create a directory for the Informix dbspace ( chunk files ).
• Create a directory for the Rational® Synergy databases (for example, /data/ccmdb).

70. What is 3-Tier architecture model?

Ans:

71. What is IBM Informix on cloud?

Ans:

The IBM® Informix® on Cloud offering provides an Informix database on IBM Cloud®. … Informix on Cloud brings you a high-performance engine that integrates time series, spatial, NoSQL and SQL data together with easy access through MQTT, REST and MongoDB APIs.

72. Is Informix a Rdbms?

Ans:

Informix is an RDBMS, coincidentally started its life from a company by the name of Relational Database Systems or RDS. The database product was acquired by IBM in 2001 and is now fondly referred to as IBM Informix.

73. How do I find my Informix version?

Ans:

For the database engine, the easiest method to find the version is to use the command line: ‘onstat -‘ (in the engine environment, while the engine is online). When you are seeking to identify the version for an Informix product other than Informix Dynamic Server, many Informix product commands have a ‘-V’ option.

74. What is the meaning of Informix?

Ans:

relational database management system

Filters. A relational database management system (DBMS) from IBM that runs on a variety of Unix platforms. Originally developed by Informix Software, Menlo Park, CA, the product was acquired by IBM in 2001.

75. Is IBM a Db2 mainframe?

Ans:

Db2 for z/OS is a relational database management system that runs on the mainframe. … IBM® offers a family of Db2 products that run on a range of operating systems, including Linux®, UNIX, Windows, IBM i, VSE, VM, and z/OS.

76. How do I run a query in Informix?

Ans:

DBAccess DBAccess is an Informix utility that allows you to operate on an Informix database:

• To use SQL query,
• Choose the “New” option.
• Enter the SQL query.
• After editing the query, press
• Select “Run” option to execute the SQL query.

77. How do I access the Informix database in Linux?

Ans:

create the odbc. ini with the desired configuration. set the DNS name (is the Infdrv1 at the example).

export the ODBCINI variable pointing to your odbc. ini file , or create the $HOME/. odbc.

try connect to the database executing : isql <'dns_name> <'user> <'passwd>

78. How do I connect to Informix with IBM?

Ans:

• Select the driver IBM Informix ODBC DRIVER .
• On the Connection tab, specify: The Informix server name. The server host name
• Click Apply.
• Click Test Connection to check your supplied values.
• Click OK to close the ODBC Data Source Administrator.

79. What is the Informix database server?

Ans:

IBM® Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.

80. Explore the IBM cloud architecture center?

Ans:

81. What is IBM Informix Connect?

Ans:

Applications that run on client computers require IBM® Informix® Connect to access database servers. Informix Connect is a runtime connectivity product that is composed of runtime libraries that are included in Client SDK.

82. How do I create an Informix ODBC connection?

Ans:

• Set up an ODBC data source on Windows
• Open the Windows ODBC Data Source Administrator dialog box.
• Click the System DSN tab.
• Click Add.
• Choose the IBM Informix ODBC DRIVER and click Finish.
• Create the administrator’s data source by typing the name of the data source in the Data Source Name text box.

83. What is Informix ODBC driver?

Ans:

The IBM Informix ODBC Driver is a powerful tool that allows you to connect with live data from IBM Informix, directly from any applications that support ODBC connectivity. Access IBM Informix data like you would a database – read, write, and update IBM Informix databases through a standard ODBC Driver interface

84. How do I start an Informix window?

Ans:

To start the database server by using the Control Panel:

• Select one of the following options: Start > Control Panel > Administrative Tools.
• Double-click Services.
• Double-click Informix IDS – server_name from the list and specify the appropriate start options or accept the default ones.
• Click Start.

85. Is IBM Informix free?

Ans:

IBM Informix Express Edition is ideal for third-party developers who want to embed a database within their applications. Available on all supported platforms, this edition is limited to four cores and a total of 8 GB of RAM. No upfront costs — ideal for application and third-party developers.

86. Is Informix the same as Db2?

Ans:

Informix is often compared to IBM’s other major database product, DB2, which is offered on the mainframe zSeries platform as well as on Windows, Unix and Linux. Informix is generally considered to be optimized for environments with very low or no database administration, including use as an embedded database.

87. How JDBC Driver connect with Informix?

Ans:

• Required File(s): ifxjdbc.jar
• Java Driver Class: com.Informix.jdbc.IfxDriver
• URL: jdbc:Informix-sqli://{HOST}:{PORT}/{DB}:Informixserver={PARAM}

88. What is Connect to Informix using DbSchema Free Edition?

Ans:

• Select an Alias for your database connection. This will be the name of this specific connection to the database.
• Select ‘Informix’ from the list of DBMS (Database Management Systems).
• The driver for your database will be automatically downloaded for you in the folder
• C:\Users\YourUser\.DbSchema\drivers\Informix (Windows) or
• /Users/YourUser/.DbSchema/drivers/Informix (Linux and MacOS).

89. Define Informix JDBC Driver?

Ans:

This article will explain what JDBC drivers are, how to download the Informix JDBC driver and how to connect to Informix using DbSchema Free Database Designer.

90. What is IBM Informix client software architecture?

Ans:

91. What IBM famous for?

Ans:

IBM, in full International Business Machines Corporation, leading American computer manufacturer, with a major share of the market both in the United States and abroad. Its headquarters are in Armonk, New York.

92. What IBM stands for?

Ans:

International Business Machines.

93. What is chunk in Informix?

Ans:

A chunk is a physical portion of disk on which Informix stores its data. A chunk can be either a raw partition or a file system file. Informix suggests that a chunk’s name be a symbolic link to the actual chunk. For example, if you are using /dev/rdsk/c6t0d0s1 as a chunk, you could create a symbolic link named /dev/Informix/chunk1 that points to /dev/rdsk/c6t0d0s1. That way, if there are ever any problems with that disk, you could replace the disk with another one and just change the symbolic link.