Installation guide

● After users have finished updating one of the sample databases, instruct them to issue the rollback

transaction command to undo the changes.

9.6 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 I/O are simultaneous, and that 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 installation software. Doing so destroys

all existing files on that partition.

● A raw partition designated for use by by any other software application cannot be mounted for use by the

operating system for any other purpose, such as for file systems or swap space.

● After a 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 I/O.

● To determine whether a device is a block device or a character device, run:

ls -l <device path>

9.6.1 Choosing a Raw Partition

Select a raw partition on which to create and mount database devices.

Procedure

1. Determine which raw partitions are available.

2. Determine the sizes of the raw partitions.

3. From the list of available raw partitions, select a raw partition for each device.

4. Verify with the operating system administrator that the partition you have chosen is available.

5. Make sure the "sybase" user has read and write privileges to the raw partition.

Note

For more information on choosing a raw partition, see your operating system documentation.

Installation Guide for Linux

Postinstallation Tasks