Raw Devices

[michaelwild]

I am installing Informix DBMS on a PC running SCO 5.04. The documentation suggests using raw disk space rather than cooked files. I have one Unix partition for the hard drive. It takes up the entire drive. Do I have to re-install Unix and leave space "open" for a raw device? This is a learning exercise so re-installation is no problem.

Also, how do you "create" a raw device? I can't find any help in the Unix documentation. I am supposed to create the raw device then link the raw partitions.

 

[Annihilannic]

You would have to reinstall and allocate a raw database division (not partition) at the divvy step.

When you choose "Use entire disk for UNIX" SCO fdisk creates one large partition occupying almost all of the disk. Then you use divvy to divide that partition into up to 8 divisions, some of which will contain filesystems such as /dev/root, /dev/swap, etc. Create one division called informix of type NON FS, and you can add a Dbspace to informix referring to /dev/rinformix.

Maybe you could make your life simpler by adding another hard drive for this purpose? Annihilannic.

 

[michaelwild]

So you are saying that I can't use divvy now to divide that single partition into "divisions"? Also, if I do re-install, just by creating & naming a division that is a NON FS I have created a raw device?

Adding another hard drive is an option. This is a non-production system I am using for self-education.

My production system was put together by the software vendor. The databases are in rootdbs and use cooked files. I don't think that is the optimum configuration but it has worked well for over 4 years.

 

[Annihilannic]

It's most probably divided into divisions already. Unless you can locate a tool that can resize HTFS filesystems you can't adjust the size of the division without breaking the filesystem. You could perhaps back the contents up, resize an existing division, recreate the filesystem and then restore its contents.

Unless the database is very heavy on I/O you should get away with cooked files though, and they are much more manageable. Annihilannic.

 

[stankow]

I'm using SCO+informix since 1992. Informix raw divisions are faster not by persents, but up to order of magnitude. So it's worths to train.

fdisk separates disk space on partitions. Divvy separates the Unix partition on "divisions". For every division and partition there exist a raw special file. If onto division is builded file system, there exist also cooked file. Look on the output of divvy and fdisk and you easily will recognize when they automatically are run by installation procedure.

Make Non FS divisions by divvy and give them to Informix. It calls them "chunks". It is possible to destroy existing file system and give it space ot informix. Also if Informix do not use it any more it is possible to build fs on that disk space. Without reinstalling the root file system.

Best variant is to use second disk. Add it to Unix, just to create special raw files, pointed to them. Give it to informix and it will be very happy with it. This variant is fastest, because drive head movement of both disks do not interfere. One disk is looking for programs, in same time the other looks for Informix records.

Stankow,

http://www.noac.biz