YUM download only mode

How many times I was in a situation I needed to update a server with RHEL installed but I wasn't at site and I didn't have a way how to reboot the server after installing a new kernel or glibc package on it reliably? Yes, I have a test environment and I'm testing the updates on it but many installations are too critical to just run yum update -y and then shutdown -r now. On top of that, there are well known Murphy's laws which are able to damage more than we are able to imagine.

Instead of remote resolution of why the server is suddenly unresponsive I'm trying to prepare some offline update archive (if there isn't an update server available but this is another situation) and then during a site visit to apply it.

As I'm talking about RHEL I'm using YUM or Yellowdog Updater Modified for it. This tool is able to download updates locally without installing them if we have RHEL 5.x system. It only requires to install a download plugin which is part of yum-downloadonly package. Try to install it with


yum install yum-downloadonly

The next lines contain common commands that I use for downloading updates:

yum install PACKAGE_NAME.rpm -y --downloadonly
yum update -y --downloadonly


If we have a RHEL 4.x server we don't have this package and we need to install another package called yum-tools which contains similar tool yumdownloader.


yum install yum-tools -y

Here it is how to use the tool

yumdownloader PACKAGE_NAME.rpm


If we wan't to download all the available updates with yumdownloader we need to get a list of all packages with yum check-update and then to pass it to yumdownloader. You can do it from shell with sed, cut or awk commands or what would you prefer:

for PKG in `yum check-update | cut -d' ' -f1`; do
   yumdownloader $PKG
done

For more detailed description of the tools and their parameters have a look at their man pages.

Time to continue

After almost a whole year, I would like to awake my blog from a sleep and begin to publish articles more regularly. During the previous period I was too busy at work and I couldn't afford to take care of it as I would like. On the other hand, I had an opportunity to participate on some interesting projects and I needed to solve many unusual tasks. Everything was written down and now it is waiting for readers and comments.

I hope the new articles will be interesting and helpful for you as the previous ones.

Red Hat Enterprise Linux 5.5 - what's new?

It's a few months since RHEL 5.5 was released (march, 2010). Despite this, I would like to point out the major changes and additions compared to the previous release RHEL 5.4. So what's new:

• Kickstart installation - it is possible to exclude package groups in the same way like single packages.
• KVM guests and Cluster Suite - management of KVM based virtual guests with Cluster Suite is supported.
• SPICE - RHEL 5.5 includes components of Simple Protocol for Independent Computing Environments which is competitor for VMware's PCoIP or Citrix's HDX.
• PCI passthrough - physical PCI devices attached to virtual guests are working better.
• Huge page support - it is extended to virtual guests with libvirt.
• Windows 7 support - new samba3x packages supporting Windows 7 are included.

For more details read the RHEL 5.5 official release notes.

VMware Workstation 7.1 enhancements

I have decided to update my current VMware workstation 7.0.1 installation I have on my desktop to the latest available release 7.1. Further follows a quick comparison of the most interesting features and enhancements between these two releases:

• WS7.1 officially support many latest versions of well-known Linux distros like RHEL/Debian/Ubuntu
• WS7.1 supports OVF1.1 via ovftool which is part of the installer
• WS7.1 has higher limits for guest's vCPUs - from 4 to 8 and guest's virtual disk - from 950GB to 2TB
• WS7.1 is capable of automatic downloads and updates of WMware Tools

Eventually, I would like to remember what new features VMware Workstation 7.0 came with:

• 32GB of guest's virtual RAM
• cross-platform license serial numbers
• pause running guest instead of suspending it or even powering it off
  
• import of Windows XP mode virtual machine
• GUI editor for virtual networks
• support for Windows 7 as guests
• support ESX hypervisor running as guest

That's not everything at all. The official release notes for VMware Workstation 7.1 and 7.0 are more comprehensive.

SLES 11 SP1 released

I have decided to write a brief summary of new features and enhancements which are available with the first service pack of Novell's SLES 11. I need to know the major differences between GA and SP1 release during my every day work and perhaps, it will help you in the same way like me. The original post about SLES11 GA is here. So, what's new?

• it is based on GNU/Linux kernel 2.6.32
• it provides web based YaST for remote management called WebYaST
• UEFI booting (useful with disks larger as 2TB) is supported on AMD64/Intel64 now
• it includes many driver updates (e.g., QLogic/Emulex HBAs, Broadcom NICs)
• it includes new XEN 4.0
• KVM hypervisor is now fully supported, good news
  
• it fully supports the latest enterprise Intel XEON 5600 and 5700 processors which are able to greatly improve performance of XEN hypervisor by decreasing latency of VMs
• finally, it contains all the latest security and bug fixes available since the release of GA

It seems there weren't so many changes included in SP1 but I think XEN 4.0 or KVM support from Novell is enough to move our GA installations to SP1. With XEN 4.0, we are able to benefit from these nifty features:

• fault tolerance
• memory overcommitment
• USB paravirtualization and VGA pass-through
  
• live snapshots and clones
• 64 vCPUs per VM
• 1TB RAM per XEN host
  

Now, it depends how fast and how successfully Novell will be able to implement and adjust these features into their management tools like YaST.

For more comprehensive contents about SLES11 SP1, check the oficial release notes at www.novell.com.

Second edition of VMware Site Recovery Manager is out

The second edition of VMware SRM, officially named as VMware vCenter Site Recovery Manger 4, was released recently. The product is responsible for automated disaster recovery of complex virtual environments. The recent version is fully compatible with VMware vSphere platform and provides these new important features:

• many-to-one failover - this means that one site is able to recover from multiple sites failures
• expanded support of storage vendors - those who provides storage replication solutions over FC, iSCSI or NFS, 12 generally. Among them belongs DELL, IBM, HP, EMC, LSI and others.

For more information on VMware SRM 4 visit the release notes and product home page.

VMware Server 1.0.x library dependency problem

In the beginning of the year, I wrote this article about some problems between older VMware server 1.0.x and newer Linux distributions. The problem is related to the vmware kernel modules whose source code are not compatible with newer Linux kernels.

I was surprised with one thing. When I upgraded VMware Server from version 1.0.8 to 1.0.9, VMware Server console stopped working. The new version was installed on the same system (OpenSUSE 11.1) as the old one, so I don't understand the reason. The important thing is I found a solution. The new version began producing these new error messages after trying to run vmware command:

/usr/lib/vmware/lib/libgcc_s.so.1/libgcc_s.so.1: version `GCC_4.2.0' not found (required by /usr/lib/libstdc++.so.6)
/usr/lib/vmware/lib/libgcc_s.so.1/libgcc_s.so.1: version `GCC_4.2.0' not found (required by /usr/lib/libstdc++.so.6)
/usr/lib/vmware/bin/vmware: symbol lookup error: /usr/lib/libgio-2.0.so.0: undefined symbol: g_thread_gettime

I have tried to unset this environment variable influencing behavior of GTK2 applications:

unset GTK2_RC_FILES

Otherwise, the variable is referencing related gtkrc files defining GTK2 user's environment. Try it and I hope it will help.

Red Hat Enterprise Linux 5.4 released

Today, it was released a next minor version of Red Hat's flagship Linux distribution RHEL 5.4. Here it is a brief summary of new features and updates:

• KVM hypervisor - Full support of Kernel-based Virtual Machine is included now. XEN support is included as well, but you can't use both XEN and KVM at the same time. Each hypervisor requires different kernel. You need to have 64b machine to run KVM. It supports RHEL 3/4/5 or Windows XP/2003/2008 as guests.
• KVM paravirtualized drivers - They are available for Windows XP/2003/2008 in package virtio-win.
• FUSE support - New version includes modules for Filesystem in Userspace (FUSE) and related utilities. Support for the XFS was added as well. It icnludes updates of CIFS and EXT4 filesystems.
• Infiniband drivers - It contains some portions of prepared Open Fabrics Enterprise Distribution (OFED) 1.4.1.

New release of RHEL contains many other updates and enhancements which aren't mentioned here. For more details read the RHEL 5.4 official release notes.

VMware vSphere hotplug

Hotplug of virtual hardware is attractive feature of VMware ESX 3.x/4.x. In case of ESX 3.x it is limited to hotadd of virtual disk to a running virtual machine only. With next generation of VMware vSphere hypervisor you are able to hotadd of memory or CPU to a machine if guest operating system supports it.

I was surprised during vSphere evaluation how it pretty works. I used to hotadd of virtual disks to my machines quite often. But when I upgraded 3.5 infrastructure to new vShpere 4.0, I became disappointed because it stopped working.

The reason why is simple. Hotadd feature is available from advanced edition only and I was upgrading to standard edition which doesn't contain license for it. You can check it in my previous post VMware vShpere 4.0 editions . Below is an error message which is complaining about missing license:

I think it wasn't a right decision to shift the feature to the higher editions. I think it would be better to leave things where they were because people are used to using them. And I hope that VMware will push back at least hotadd of virtual disk in some future release of vSphere.

Linux rc.local script

Sometimes, you need to run some commands during your Linux server startup. And you don't want to waste time with preparing valid init script now. The common task is to load some kernel module or to change speed of network interface and so on.

Red Hat distributions provides for this task rc.local script. You can find it in the directory /etc/rc.d. The script is executed after all the other init scripts. This is ensured with the proper START scripts linking to the /etc/rc.d/rc.local script:

/etc/rc.d/rc2.d/S99local
/etc/rc.d/rc4.d/S99local
/etc/rc.d/rc3.d/S99local
/etc/rc.d/rc5.d/S99local

SUSE distros like SLES or OpenSUSE provide similar mechanism. You have available two scripts. The before.local script should contain everything you want to run before runlevel is entered. The after.local script works like RedHat's rc.local script. It contains stuff which should be executed after runlevel is reached. The scripts don't exist by default, you need to create them at first in the directory /etc/init.d. They don't have to be set executable.

Besides this, the RedHat's rc.local script is executed only in runlevels 2, 3, 4 or 5. It is ignored in the single user mode. SUSE's version of after.local or before.local is interpreted during all runlevels including runlevel 1.