October 30, 2007 Lunch on Linux Webcast“Unix to Linux Migration”

FAQs

Question 1: Why is Red Hat slow to adopt most of the Fedora code base changes?

Answer: Red Hat Enterprise Linux technology is derived from the Fedora Project. Fedora is a Red Hat-sponsored and community-supported open source project. It provides a public development platform and proving ground for new open source technologies. Fedora features that are proven mature and stable are incorporated into commercial Red Hat products. The Fedora Mission Statement is: “Fedora is about the rapid progress of Free and Open Source Software”. Releasing new versions every 4 to 6 months. With this said, Red Hat has a version release of about 18 months. Fedora's main objective is to contain only free and open source software, but to also be on the leading edge of such technologies. (See Link).

http://fedoraproject.org/wiki/Objectives

Fedora developers perfer to make upstream changes instead of applying fixes specifically for Fedora, this ensures that updates are available to all Linux Distributions.

Red Hat Enterprise Linux technology is derived from the Fedora Project. Fedora provides a public development platform and proving ground for new open source technologies. Fedora features that are proven mature and stable are incorporated into commercial Red Hat products. The key word is proven mature and stable. Sometimes this can take a while. And Red Hat likes to make sure it is mature and stable before it hits the critical server market.

Fedora Core releases are issued about 2-3 times a year and are available from Red Hat servers and more than 200 mirror sites worldwide. However, the leading-edge, rapidly changing nature of Fedora makes it impractical for use in commercial environments, and it is not formally supported by Red Hat or its ISV/OEM partners.

New versions of Red Hat Enterprise Linux are released approximately every 18 months, after a rigorous development and testing period. Each release is supported with updates and security enhancements for seven years, during which time Red Hat maintains the highest possible levels of stability and consistency. This ensures that applications continue to run without the need for rebuilding or recertification. It is the stable environment offered by Red Hat Enterprise Linux that makes it the preferred platform for ISV and OEM product certifications, and therefore ideally suited for commercial deployments. A great link to read.

http://www.redhat.com/rhel/migrate/whichlinux/

Question 2: Are there recommendations for how many guest OS can be supported according to hardware available?

Answer: Red Hat can run an unlimited amount of Guests depending on the Amount of RAM and CPUs in the host. With RHEL 5 Advanced Platform, they are fully supported. YEP!!! All of them... and for the cost of 1. There are many variables to consider when recommending the number of Guests to use. If you have a fixed amount of RAM, you would have to look at specific applications being run and do some benchmarking.

A great tool to do this is xentop which displays real-time information about a Xen system and domains (e.g, CPU utilization and Memory utilization). The xentop utility provides and interactive display of continuously updated status and performance information about active domains. This is similar to the top utility and its display of information about processes.

CPUs are the actural physical CPUs in the computer. The Xen Hypervisor controls and allocates the CPU resources as used by the domains. This ensures that the amount of CPU time consumed b a domain may be explicitly limited.

It is also important to define and reserve enough capacity for Domain-0. If xen is running very demanding applications, consider reserving one physical CPU entirely for Domain-0 (DOM 0). Avoid configurations where Dom 0 can become unresponsive due to a lack of available resources. A domain is the Xen term for the virtual machine in which an operating system runs.

A great Xen resource is: https://virt.108.redhat.com/

More info at: http://www.redhat.com/rhel/virtualization/

For further xen commands visit the 108 website and runt the command `man -k xen` :-)

Question 3: I also thought that you have to have a specific CPU to be able to use full virtualization? Not all servers can support this os?

Answer: Xen is very flexible in terms of the minimum hardware required to setup a Xen environment and run one or more domains. You are correct in that you have to have a specific CPU to be able to use virtualization. Intel's VT-x technology and AMD's Pacifica technology allow operating systems with no native Xen support to run on Xen.

It should also be noted, that while not a minimum requirement to run Xen, shared storage allows for the most flexible configuration options. Live Migration of a domain from one physical host to another is only available with shared storage.

Question 4: Where can I get RHEL system administration training?

Answer: Red Hat offers Industry-acclaimed // Performance based training programs which offer the most current and accurate hands-on training courses, and the most respected certifications in the Linux space.... Guaranteed.

Please see our RHCT (Red Hat Certified Technician) and our RHCE (Red Hat Certified Engineer) Courses here:

https://www.redhat.com/training/

We also offer specific training courses noted on this page: (for security, developers, and applications).

Question 5: Is Xen(Zen?) automatically installed with basic RHEL?

Answer: To install Xen you will have to confirm that the RHEL server has a virtualization entitlement, (this comes with RHEL 5), and it is subscribed to the virtualization channel.

Make sure that you have the following installed required packages. [kernel-xen , virt-manager, xen]

#for i in kernel-xen virt-manager xen ; do rpm -qa | grep -i $i ; done

Make sure that kenel-xen is the default kernel to boot within /boot/grub/grub.conf. The default line indicates which kernel is the default to boot from. You can run the command: `xm list` to see if Dom 0 is running.

If Dom 0 is not running start the xend service with the command: `service xend start`

Our https://virt.108.redhat.com/ site will help you install guests via some hand written labs.

Question 6: What about competitive pricing with Microsoft?

Answer: I don't think that you can get any better RHEL pricing. You buy one Red Hat Enterprise Linux Advanced Platform, and you can run unlimited guests for free and they are supported. If you run a Microsoft guest, you will have to pay for each Microsoft instance that is running.

Question 7: LVM, GFS, EXT3: Is there something which lays out pros and cons for each?

Answer: Ext3 and most filesystems, are designed to be used by a single host. For these single-host filesystems, filesystem corruption can result when multiple hosts mount the same block storage device.

By using a cluster filesystem such as GFS, it is possible for multiple hosts on the Ethernet network to access the same block storage using ATA over Ethernet. There's no need for anything like an NFS server, because each host accesses the storage directly, distributing the I/O nicely.

Storage technology plays a critical role in increasing the performance, availability, and manageability of Linux servers. One of the most important new developments in the Linux 2.6 kernel—on which the Red Hat® Enterprise Linux® 4 kernel is based—is the Linux Logical Volume Manager, version 2 (or LVM 2). It combines a more consistent and robust internal design with important new features including volume mirroring and clustering, yet it is upwardly compatible with the original Logical Volume Manager 1 (LVM 1) commands and metadata.

For more information on LVM please read:http://www.redhat.com/magazine/009jul05/features/lvm2/

A great GFS link to help you with your decisions is: http://www.redhat.com/gfs/

For more information on Ext3 please read: http://www.redhat.com/support/wpapers/redhat/ext3/why.html

Question 8: I’ve implemented some other types of clustered filesystems in the past.  I’m looking to build a redundant NFS system.  Would you please forward me any details that you have on GFS with regards to Installs.  In other words, if you have any GFS related links, I”d appreciate it if you’d forward those links to me.

Answer: Here are some great links on GFS for you....

http://www.redhat.com/gfs

http://www.redhat.com/whitepapers/solutions/RH_GFS.pdf

All you need to know and more: :-)

http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/Global_File_System/index.html

Question 9: What package does the makewhatis command come in?

Answer: if you run the comand:#rpm -qf `which makewhatis`

The answer will be.... man-1.6d-1.1

Question 10: What is a xendump?

Answer: Xendump is a facility for capturing vmcore dumps from Xen guests. It is built-in to the Xen Hypervisor. Vmcore dumps are useful for analysing system crashes, using the tool crash. Crash is similar to traditional Unix crash tool, and it provides stack traces and other debugging functionality for locating problem areas causing the crashes.

Crash is a tool for interactively analyzing the state of the Linux sys-tem while it is running, or after a kernel crash has occurred and a core dump has been created by the Red Hat netdump facility.

Question 11: Where can I find out more info on RHEL and Common Criteria?

Answer: http://www.redhat.com/solutions/government/commoncriteria/

Question 12: I would like to have more information on comparing Solaris and Linux commands, can you point me in the right direction.

Answer: Check out the IBM redbook, it is awesome. http://www.redbooks.ibm.com/abstracts/sg247186.html