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RCHE Red Hat Certified Engineer Linux Study Guide[c] Exam (Rh302) Authors: Jang M. H. Published year: 2003 Pages: 34-35/194 |
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Most new computers come with very large disks, easily supporting even the 4GB of files associated with a full installation of Red Hat Enterprise Linux. If you do not have this much space available, you should carefully consider the space requirements associated with each type of installation. When considering the following options, remember to leave adequate room for swap space, personal files, log files, and any applications that you may want to install after RHEL installation is complete.
| On The Job |
It's common to install Linux on older computers with limited hard disk space. Linux functions quite well on older computers. It's common to configure such computers as servers for DNS, DHCP, NIS, and more. However, RHEL 3 does require at least Pentium-level 200 MHz CPU support, so you can't install it on the oldest computers |
The question of disk space needed over and above operating system needs is always relevant. Make sure to have extra room. The absolute minimum for a Red Hat Enterprise Linux OS is around 600MB of disk space, if you install Linux with few server services and without the X Window System. With 1000MB, you could probably sneak in the X Window, but you still wouldn't have enough room for more than a few server services. You still should have at least 100MB or more to work with. And if you want GNOME or KDE, you'll need another 200MB or so.
You'll also need to add room for swap space. By default, Red Hat usually configures a swap partition that is about twice the amount of RAM on your computer. The minimum requirement in RHEL 3 is a swap partition that equals the amount of RAM on your system. The actual swap partition size depends on the RAM and the size of the hard disk on your system.
The actual amount of swap space that you may need is a highly debatable issue. Some suggest that Linux computers can use a swap partition that is up to three or even four times the amount of available RAM. Others suggest that at higher levels of RAM, 100MB of swap space is more than sufficient.
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By default, the RHEL installation program configures multiple volumes-separate volumes associated with different directories. The advantage of separate partitions for certain directories is that it limits the risks to your system. For example, many Webmasters configure their Web sites to write daily log files with data relating to all users who visit their sites. These files can become quite large, especially for large online merchants .
Before you decide how to set up partitions, you need to know about each of the major Linux directories. Linux directories are organized according to something known as the Filesystem Hierarchy Standard (FHS).
The FHS is a standard for organizing directories for Linux- and Unix-based systems. Every FHS-compliant operating system starts with a top directory, root, symbolized by the forward slash. All other directories are subdirectories of root. The major FHS directories are described in Table 1-1 in Chapter 1.
Unix was developed when disk space was miniscule by today's standards. As Unix became an operating system for larger companies and universities, administrators had access to multiple, separate physical disks for each Unix computer. They took advantage of the space by splitting up the filesystem into smaller, more manageable pieces. Different directories were mounted on different physical drives .
This has a number of advantages. Smaller partitions are easier to maintain. Smaller partitions are easier to back up and restore. The size of a partition can limit the space taken by any specific directory. You can set up specific partitions as 'read-only' for additional security.
There is at least one case where you should not mount different Linux directories on different partitions. If you're limited to a smaller hard drive, you need all of the spare room that you can get. This may apply to an older laptop computer, or an older computer that you're using for a dedicated purpose, such as a DNS server or a gateway router.
When you set up an RHEL Server filesystem, you can let Red Hat configure the partitions for you. By default, Red Hat configures a root directory (/) and a /boot directory partition.
Additional filesystems can be mounted on separate partitions to meet additional or specific needs of related groups of users. Some examples include: /home, /usr, /var, /development, /dbms, /financials, /inventory. The /tmp directory is often also mounted on a separate partition, to limit the space allocated to what should be temporary storage.
| Exam Watch |
As befits a standard Linux server, it's quite possible that you'll need to configure several filesystems on different partitions during the Installation and Configuration exam. |
Dedicated services are also good candidates for separate filesystems. For example, specific applications such as Web and FTP services can take up gigabytes of data. They store files in the /var/www/html and /var/ftp/pub directories.
You want to protect the rest of your computer if problems arise with a specific service. File and print sharing services such as NFS and Samba present security risks because they expose shared directories to other users. If you don't mount these services on separate partitions, anyone who uploads a large number of files could conceivably fill your hard disk.
If the number of files and users are large, you may even want to spread shared files over several partitions on different physical drives. In this situation, not every user will want data from the same drive all of the time. The load is shared by the different drives. Performance is improved.
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RCHE Red Hat Certified Engineer Linux Study Guide[c] Exam (Rh302) Authors: Jang M. H. Published year: 2003 Pages: 34-35/194 |