what is the difference between RHEL4 & RHEL5?
RHEL4 :No yum server,Selinux,secure,no cd key
RHEL5: yum server, advanced selinux ,more secure,virtualization
RHEL4 : Stable Kernel, Can'nt create YUM repository,
Selinux with 36,000 lines of code, Quite secure,no cd
key,no Xen.
RHEL5: Not stable kernel, Can create yum server, advanced
selinux without line of codes these are converted into
modules ,more secure,virtualization with Xen, As comapre to
RHEL 4 Many bugs in RHEL5 for e.g. Reducing LVM.,
IPV6 implementation.. etc
difference between RHEL 4 and RHEL 5
1)In RHEL 4 SELinux Block only 13 services, But on RHEL 5
SElinux Block 80 services
2) RHEL 4 have ext2 filesystem, but RHEL 5 we have ext3
filesystem That support Journal
3)RHEL 4 have no virtualization Feature, but in RHEL 5 we
have virtualization with Hypervisor-V
4)In RHEL 4 we have no Yum, But in RHEL 5 we have Yum available
differnece between rhel 4 and rhel 5
rhel4 rhel5
no yum server yum server
selinux Advanced selinux
secure more secure
no cdkey cd key
--- virtualization
mim 256 mb ram 512 ram
--- better support for
Red Hat Directory
XEN, YUM and improved SELinux
all the features updated with better options
Better GUI support then RHEL4
YUM over RPM package management
IPTables and SELinux for more secure environment
Red Hat author dishes on RHEL 5
By Jack Loftus, News Writer
23 Apr 2007 | SearchEnterpriseLinux.com
Enterprise Linux headlines
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Tammy Fox has worn many hats in the past for Red Hat Inc., including technical writer, lead of the documents team and founding editor of Red Hat Magazine. She has also been a professional Linux writer for the past seven years. In other words, she knows Red Hat Linux.
Five things to know about RHEL 5:
1. Installation codes are necessary for installation and can unlock access to specific functionality such as virtualization and clustering.
2. Virtual machines can be created with the virtualization option, which is based on Xen.
3. Kdump can be enabled to capture dump files during system crashes.
4. YUM has replaced up2date, both the command and graphical application.
5. SELinux is enabled by default.
- Tammy Fox, author, Red Hat Enterprise Linux 5 Unleashed
Fox's latest work, Red Hat Enterprise Linux 5 Administration Unleashed, arrived this month intended as a tome of knowledge for intermediate to advanced Linux system administrators. Before it was published, Fox sat down with SearchEnterpriseLinux.com to provide some insight on the latest version of the Linux community's leading commercial distribution, Red Hat Enterprise Linux 5 (RHEL 5).
What general best practices or tips can you share to make an upgrade to RHEL 5 a smooth one?
Tammy Fox: Performing an upgrade with the installation program basically updates any existing RPM packages on your system. If the new version of the package includes changes that make your existing configuration invalid, some packages will try to migrate your existing data, but it is not required.
The best practice is to have your data on a dedicated storage system that does not get reformatted during a fresh installation. Depending on the size of your organization, this can be a SAN, a data cluster, or just a set of dedicated hard drives in the system. Back up any existing data and configuration files, and perform a fresh installation. Restore your configuration files one by one, testing each program. Be sure to pay close attention to whether or not the software version has changed from your previous version of RHEL to RHEL 5. Finally, reconnect your data storage solution and perform any additional tests necessary.
Of course, all of these steps should be performed on a test system before the plan is implemented on a production system.
What are some key differences between what administrators see in RHEL 4 deployments, and RHEL 5 ones?
Fox: The most immediate change they will notice is the introduction of installation codes. During installation, an installation code must be entered. These codes are generated by Red Hat. Depending on what services you purchased, they unlock different RHEL 5 components such as virtualization and high availability. RHEL 5 also uses new RPM GPG keys. If upgrading, you will need to install the new keys before updating packages.
The next big noticeable change is the move to YUM for software management and maintenance. In previous versions of RHEL, the up2date command could be used to download and install software updates from Red Hat Network. It has been replaced with the YUM command, and all the up2date graphical program has been replaced with a graphical program that use YUM as well. If you schedule package updates and installation with the RHN Web site, you will not notice a difference.
Administrators must also consider whether to use the virtualization feature in RHEL5. (Editor's Note: Due to trademark issues, Red Hat currently refers to Xen-based hypervisor technology as virtualization.) If your hardware is supported and you have systems with enough resources to share between the host system and the virtual machines, virtualization can help reduce the number of physical machines that need to be maintained. If you are a hosting service or allow your customers shell access to their Web site, virtualization can be beneficial.
Administrators should read the release notes for a complete list of caveats and known issues with RHEL 5. For example, dual-booting with Windows Vista requires additional steps for GRUB to boot Windows Vista.
