Sybase Adaptive Server IQ 12.4.2, Administration And Performance Manual

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Balancing I/O
444
Disk striping option
This section explains how you can use the option Adaptive Server IQ provides
to do disk striping, without using third party software. If you already have a
disk striping solution through third party software and hardware, you should
use it instead.
Turning disk striping
on or off The syntax you use to turn disk striping on or off is:
SET OPTION "PUBLIC".DISK_STRIPING = { ON | OFF }
The default is
ON
for UNIX systems, and
OFF
for Windows NT systems. When
disk striping is
ON
, incoming data is spread across all dbspaces with space
available. When disk striping is
OFF
, dbspaces (disk segments) are filled up
from the front on the logical file, filling one disk segment at a time.
As with all
PUBLIC
options, you must disconnect and then reconnect in order
for the change to take effect.
When disk striping is on, you cannot drop dbspaces with the
DROP DBSPACE
command. Since dbspaces are dropped as they are empty from last to first, and
with this strategy dbspaces are filled partially in a more distributed manner, it
is unlikely the dbspaces will be empty. If you want to be able to drop dbspaces,
you should set
DISK_STRIPING
to
OFF
.
Disk striping hints
Here are several different ways to think about distributing space on a large disk
drive, for example 9GB:
1 Use different segments in different databases.
2 Mix them into the usage list with segments from different disk drives in
between.
3 For the best multiuser performance, set your operating system or disk
array to the maximum stripe size it supports.
Here is a good example: