Re: DBCS and disk space

Thank you Simon.  You've always been a great source of information.

Rob Berendt
-- 
"They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety." 
Benjamin Franklin 





"Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>
Sent by: midrange-l-bounces@xxxxxxxxxxxx
06/05/2003 08:11 PM
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        Subject:        Re: DBCS and disk space



Hello Rob,

You wrote:
>They are in the planning stages and wanted to know the disk impact of 
>this, if any.  Might be a stupid question, but does DBCS take double the 
>disk space?

No it does not. A DBCS system will probably require more DASD than an SBCS 
system 
but it depends on how data is stored.

Program code is no different on DBCS and SBCS systems so they don't occupy 
more 
space. Files on DBCS systems are capable of holding SBCS data so existing 
single 
byte data, such as source code, will not occupy more space. Where you may 
see an 
increase in disk space is for things like message text **IF** you use DBCS 
text 
in the message body. Also translated IBM panels and message files may 
occupy more 
space.

DBCS systems allow you to define fields that contain only SBCS data, only 
DBCS 
data, or a mixture of both using ShiftOut and ShiftIn characters.

Note that all fields (database, display, print, etc) generally have a 
fixed size 
thus they occupy the same number of bytes regardless of whether they hold 
SBCS or 
DBCS data. For example a 50-byte DBCS Open field could hold 50 characters 
of SBCS 
text or 24 characters of DBCS text. In either case there is no increase in 
disk 
space used.

Most DASD increase occurs on DBCS systems simply because each DBCS 
character 
occupies two bytes and thus address fields etc. have to be increased to 
allow say 
30 DBCS characters instead of the 15 that would be allowed with a standard 

30-byte field.

Appendix E of the DDS Reference has some useful information about DBCS 
considerations.

My system is running DBCS English as the primary language. I have SBCS 
English, 
French, German, Italian, Spanish, Japanese, Korean, Traditional Chinese, 
and 
Simplified Chinese installed as secondary languages.

Regards,
Simon Coulter.
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