Oracle: Unbreak my Linux Heart

I have been getting some weird errors in some Linux VMs running on VMware ESX 3.0.x (and perhaps ESX 3.5, as we're migrating to that). The symptoms are always that some weird errors occur for users or some maintenance task, and when you check the VM's consoles, you discover that the file system is suddenly read-only. My dear friend MrVanes discovered there is a known issue with the VMware LSI driver mptscsi in VMware guests running Debian . "...one could get SCSI timeouts when there is massive workload on the host system. Some kernel versions these will get the file systems remounted read-only, which probably makes sense for real hardware, but doesn't make sense for emulated hardware. Instead it should just wait a bit longer." A savvy user called TuxyTurvy has thoroughly investigated this issue. He was using Red Hat RHEL 4 and 5 on Dell 1850 servers with a Clarion AX150i el-cheapo SAN. When I/O load got high, running under VMware, due to storage contention, SCSI t...

With the whole green motion going around, I was happy to join lesswatts.org to try and limit the power consumed by my servers. Although we use VMware extensively to bundle VMs onto ESX hosts, there still are many bare metal servers for one reason or another. We're experimenting with VMware's experimental DPM (Dynamic Power Management) to collect and pack idle VMs onto a single host. DPM then suspends the host and saves power. In the morning, when loads increase , the VMs are VMotioned off the hosts again, after these are reawakened. For Linux, I'm gonna give PowerTOP a spin and test it in the coming year to try and optimize my Oracle Enterprise Linux servers.

You may know that I've migrated from an RCS system to a Subversion (SVN) version control system. I migrated our RCS archive into a stand-alone, read-only, svn repository for reference purposes (using cvs2svn --use-rcs ) and copied all the files I personally needed into its own project folder in svnrepo/trunk/myproject. Since then I've been trying to get others to make the switch too. The other day, a colleague asked if I could transfer his files. He had kept using RCS after my import, so I tried to import his project into a separate folder off the main svnrepo trunk. I figured cvs2svn would let me set a destination directory. Well... it doesn't. I had a little discussion on the cvs2svn Mailing List . I thought it was my fault or ignorance. Turns out that you can't directly import a project into a specific svnrepo sub folder. And while it could be built, you have to realize something: The entire import would come chronologically after everything up to that point. All ta...

A never ending problem when you run Linux in the enterprise, is security (and stability) of the systems and access control to allow users, contractors, developers to install software and create or tweak configurations so that some application or service runs. Ideally, only you the sysop can install or configure software and everyone else has to turn to Using sudo , you can define tons of ways for users or groups to be able to run (or not) some commands on some or all systems. You can setup that they may run commands as other users without needing their password. Or you can turn off passwords all together. However, as soon as you start building a list of commands that a certain user or user group can or cannot run, you create the possibility for knowledgeable hackers users to work their way around your system by creating loopholes, symbolic links or abuse buffer overflows. Perhaps, we should all use sudo to allow or deny general access to machines or users and use consolehelper to cre...

Very interesting tidbit on the PowerEdge mailing list today... Dell seems to have built their DRAC remote server management interface around BusyBox Linux . It's a minimal, low profile Linux platform, often used in embedded situations or for system rescues, maintenance, upgrades and so on. BusyBox is GPL, so accordingly DRAC must be GPL and therefore the source code must be available somewhere. Well, it is ! Just file a service request and mention " SKU 420-3178 ". And this makes for low level custom builds for your specific organization, additional drivers, etc. Update: The SKU number for the DRAC source code is also mentioned in the Dell PowerEdge Diagnostics readme.txt file. Update2: Someone has thoroughly investigated the SKU with Dell Australia and the ruling is that the SKU does not exist (anymore). It can't be found. Update3: Dell releases DRAC5 source code on website.

Found a little note on Red Hat today, that mentioned to use network bonding mode numbers instead of names. Add settings to /etc/modprobe.conf but use mode={0,1,2,3,4,5,6} to enable load-balancing, active-passive, fail-over or others. Update: also check out documentation on network bonding from the Linux Foundation. Update2: Official Linux kernel documentation on network bonding .

func is a system management layer to remotely manage a whole set of systems. A bit of ssh, WBEM, keys and command lines. Check out their site! I may just give this a try...

Cobbler is a Linux installation server that allows for rapid setup of network installation environments. With a simple series of commands, network installs can be configured for PXE, reinstallations, media-based net-installs, and virtualized installs (supporting Xen, qemu, KVM, and VMware Server). Cobbler uses a helper program called 'koan' (which interacts with Cobbler) for reinstallation and virtualization support. Cobbler can also optionally help with managing DHCP, DNS, and yum package mirroring infrastructure -- in this regard, it is a more generalized "provisioning" server, rather than just dealing specifically with installations. It has a command line interface, a web interface, and also several API access options. That sounds like a lot, but it's really pretty simple.