We have been working on a project for a customer to upgrade the kernel, PowerPath, OCFS2 and other operating system patches.  The project was interesting as no single source of information existed on the appropriate process.

The procedure issue comes in because OCFS2 relies on seeing the disks which PowerPath presents.  PowerPath and OCFS2 are reliant on a particular kernel version to work properly.  With all of the inter-dependencies,  which should be done and in what order was the question. To top it off, this was also running a RHEL cluster and another instance running Oracle RAC.

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We had a client with 3000+ named users, and each of them were configured without authentication for smtp relaying, the qmail/vpopmail system they were migrating from had “pop before smtp” authentication. Well, we wanted to have as little disruption as possible for the migration so we needed to enable this same feature in Zimbra.

It is still planned to cutover the clients to SMTP Authentication, but this allows for a somewhat smoother transition.

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We have all been there before. Your server crashed, nothing indicates what happened. You check /var/log/messages and all you see is.. well.. nothing. With no sign of what happened, or indication of why it happened you are left to.. wait until it happens again.

On Red Hat based systems, you have an answer. NetDump (diskdump may work as well, more on that another time). Below we will explore the steps required to setup and test netdump.

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If you have a dedicated Linux server, this list is for you. Below are a few items you need to do, to ensure your 2008 will be a bit brighter.  This list is by no means comprehensive, but hopefully gets you started in the right direction this year.

• Check your backups and perform a full system backup (or setup a backup routine! Now!).

If you have backups configured, validate they are actually being run. Check the last date / time of the backups to ensure they are running as expected. If possible, test the restore process.

Perform a full system backup and copy this backup offsite, to a provider like rsync.net

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Here was the scenario I faced. RHEL4 machine will not boot (according to data center), receives various library not found errors on bootup (Later, I found these errors were from an intruder who tried to install a rootkit, and it didn’t go so well. Most of /bin was corrupt).

The data center recommends that the operating system be reloaded onto a separate disk, which will become the primary, and then mount the old disk as a different mount point for reference / restore. The data center reloaded the operating system, and the customer then found our services online and asked for assistance.

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When running a ‘yum check-update’, I would receive an error. The error continued even after running ‘yum clean all’.

The error is shown below:

# yum check-update
Setting up repositories
core 100% |=========================| 1.1 kB 00:00
updates 100% |=========================| 1.2 kB 00:00
extras 100% |=========================| 1.1 kB 00:00
Reading repository metadata in from local files
primary.xml.gz 100% |=========================| 1.0 MB 00:00
Traceback (most recent call last):
File "/usr/bin/yum", line 29, in ?
yummain.main(sys.argv[1:])

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