Database Reference
In-Depth Information
Considerations for swap space
Another important consideration for every Oracle installation is the amount of swap space to be provided by the
operating system. Discussing virtual memory in Linux easily fills a book on its own; nevertheless I would like to add
some information here to allow you to make an informed decision about swap size.
Simply stated, swap allows the operating system to continue running even if all physical memory is exhausted.
Technically, swap space is an extension of the virtual memory to hard disk, and can either be a dedicated partition or
a file. The use of a dedicated swap partition is recommended over the file-based approach.
For recent Oracle releases, the following formula was used and enforced in Oracle's Universal Installer:
For physical memory less than 2 GiB Oracle wants 1.5x the physical memory as swap space.
For systems between 2 and 16 GiB RAM, Oracle recommends a swap partition equal the size of
physical memory.
For servers with more than 16 GiB RAM Oracle suggests 16 GiB of swap space.
Interestingly, there are multiple recommendations made in the Red Hat documentation set about the swap size!
This shows that the amount of swap to be provided is not an exact science. Having elaborated on the use of swap for
the operating system there is one remark to be made for Oracle: your database processes should not swap. Strategies
to control the virtual memory in Linux are described later in this chapter.
Writing changes to disk
So far in the partitioning screen nothing has happened to the data on disk. As soon as you chose to continue with the
installation process by clicking on “Next” in the partitioning screen this changes.
A prominent warning pops up stating that when writing the changes to disk all deleted partitions will indeed be
erased, and partitions selected to be formatted will be lost. This is the last warning, and final opportunity to abort the
installation process without affecting the data on hard disk.
If you are absolutely sure the settings you have chosen are correct, click on “Write Changes to Disk” to proceed.
Boot loader configuration
Oracle Linux continues to use the GRand Unified Bootloader version 0.9x unlike many consumer distributions, which
have switched to GRUB 2. The installation screen does not require too much attention if you are not planning on
dual-booting the Oracle database server. As pointed out earlier, the main reason to dual-boot a production database
server is when you want to perform an operating system upgrade.
If another Oracle Linux distribution is found and correctly detected it will be added to the boot menu.
Software installation
The Oracle Linux software selection screen is not the most user-friendly interface and occasionally can be difficult to
use. The software selection screen is shown in Figure 5-5 .
 
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