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By James T. Dennis, tag@lists.linuxgazette.net
LinuxCare, http://www.linuxcare.com/

(?) Informix/SCO SE version 5.0 under iBCS

From Alvaro Gonzalez on Sun, 30 Jan 2000


I need your help. I have Caldera OpenLinux version 2.2 and i have problems using Informix-SE version 5.0 for SCO UNIX.

This software run with iBCS 2.1-1 without problems, but i have a limit in the size of the database files, 1 Giga.

I think that limits is for the variable ULIMIT of SCO UNIX, set on 1 Giga for default, and if this is true I need to set iBCS with a value greater than 1 Giga.

Thanks. Alvaro

(!) I'll be the first to admit that I just don't know as much as I want about the big SQL DBMS packages.
However the question that immediately comes to mind is:
Why don't you use the Linux version of Informix?
I have an evaluation copy for IDS (Informix Dynamix Server) version 7.30.UC7.
Is the problem here that upgrading to this will be too expensive? Is it that there are enough upgrade issues that your code and tables will take too much effort to upgrade for operations under the new server?
Assuming that upgrading/migrating to the Linux version of Informix is not an option doesn't Informix 5.0 allow you to define database file "extents" (1Gb Linux/UNIX files that their server internal manages as blocks of the large tables. I was under the impression that all of the major DBMS packages did this before the LFS (large file summit) brought support for large files to most of the 32-bit UNIX implementations. (Linux hasn't implemented LFS, though there are exerimental patches floating about to do so).
There is a ulimit command (shell built-in) and there are Linux facilities for managing the ulimit settings. These vary from one distribution to another and based on some of the packages you might have installed. For example some use the /etc/login.defs (stock Shadow suite) or the PAM pam_limits module or /etc/lshell.conf (my Debian system). However the limit you're bumping into might be with your iBCS support.
Current Linux ext2 filesystems have a 2Gb filesize limit on 32-bit systems. This is likely to change in 2.4 or 2.6 (over the next year or so). However, that's not likely to help you in the near term.
Personally I suggest that you look into the Linux native Informix server, and into the table segmenting features for that. If those don't to the trick, maybe you should contact a DBMS specialist. (We have some people at Linuxcare, where I work for my day job; that know far more about these things than I do).

[ Sadly, Informix' FAQ, http://www.informix.com/informix/products/linux/lxfaq.html notes they took out several cool features when releasing their SE suite for Linux. Perhaps they were in a rush to market, or perhaps they don't think we're really "the enterprise" so we don't care, or maybe they're merely uncertain (they say they're evaluating Linux needs). Among the features taken out were raw device support (which probably would allow use of larger spaces) and backups (!? WHat good is a big server without backups? You mean I have to turn it OFF to back it up? Ow!).

They also claim we're missing a feature I'm not entirely sure we lack (asynchronous I/O -- a Google! linux search on "asynchron*" yields plenty of info, seeming to implicate a particular flamer in the land of tainted benchmarks). If you are among those who'd hope to use it for real work, make sure to let them know your real needs at linux@informix.com).
-- Heather ]

Copyright © 2000, James T. Dennis
Published in The Linux Gazette Issue 51 March 2000
HTML transformation by Heather Stern of Tuxtops, Inc., http://www.tuxtops.com/

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