Installation guide

Maintaining Sample Databases
The sample databases contain a guest user option that allows authorized users to access the
database. Guest users have a wide range of privileges, including permissions to select, insert,
update, and delete user tables.
Sybase recommends that you remove the guest user option from user databases in production
systems. For more information about the guest user and a list of guest permissions, see the
System Administration Guide .
1.
If possible, and if space allows, give each new user a clean copy of the sample databases so
that each user is not confused by other users’ changes.
2.
If space is a problem, instruct users to issue the begin transaction command before
updating a sample database.
3.
After users have finished updating one of the sample databases, instruct them to issue the
rollback transaction command to undo the changes.
Raw Partitions on Linux
You can create and mount database devices on raw bound devices for raw disk I/O. Raw disk
I/O enables direct memory access from your address space to the physical sectors on the disk
while omitting needless memory copy operations from the user address space to the kernel
buffers.
Raw disk I/O assumes that logical and physical IO are simultaneous, and writes are guaranteed
to flush to the disk when the system write call returns. When preparing a raw partition device,
follow these guidelines:
• Do not initialize a database device on the partition that contains your Sybase installation
software. Doing so destroys all existing files on that partition.
• A raw partition designated for use by Sybase cannot be mounted for use by the operating
system for any other purpose, such as for file systems or swap space.
• After a Sybase configuration utility or the disk init command has initialized a portion of a
partition as a database device, the entire partition cannot be used for any other purpose.
Any space left on the partition beyond the size specified for the device can be reused with
the disk resize command.
• To avoid any possibility of using a partition that contains the partition map, do not use
cylinder 0.
• Place the database device on a character device, because the server recovery system needs
unbuffered system IO.
• To determine whether a device is a block device or a character device run:
ls -l <device path>
CHAPTER 9: Postinstallation Tasks
64 Adaptive Server Enterprise