Chunk limitations

Question

What are the chunk limitations in Informix Dynamic Server (IDS) and Extended Parallel Server (XPS)?

Answer

The IBM Informix® database servers have different limitations on the number of chunks and the maximum chunk size.

The following table shows the maximum number of chunks and the maximum chunk size that the IBM Informix onLine (OnLine), IBM Informix Dynamic Server (IDS), and IBM Informix Extended Parallel Server (XPS) database servers can create.

Version	Number of chunks	Maximum Chunk Size
OnLine 5.x  with 2KB pages	Varies from 12  to about 50  (see below)	2GB
OnLine 5.x  with 4KB pages	Varies from 26  to about 100  (see below)	2GB
XPS 8.1x and 8.2x	32767	2GB
XPS 8.3, 8.4, and 8.5x	32767	1 TB
IDS 7.x	2047	2GB
IDS 9.1, 9.2, and 9.3	2047	2GB
IDS 9.4/IDS 10.0	32766	2 Billion Pages

Number of chunks in onLine 5.x 

In onLine 5.x a data page is used to store information about the chunks. 28 bytes of the page are used for various structures. Out of the memory left, each chunk uses up 28 bytes plus one byte for every character in the complete path name of the chunk. So the shorter the full path names of your chunks are the more chunks you can have. 

The ranges in the table above are based on the maximum allowed path name of 128 characters and a realistic minimum path name length of 12 characters. 


Units used in this document 

This document uses the base-two definitions for memory units as follows: 

KB = kilobyte = 1024 bytes = 2 10  bytes 
MB = megabyte = 1024 KB = 2 20  bytes 
GB = gigabyte = 1024 MB = 2 30  bytes 
TB = terabyte = 1024 GB = 2 40  bytes

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