So I am not going to lie, I am a very sick man, and I am not afraid to admit it. I have a terrible, terrible addiction which is my homelab. It all started out so innocently... An old Sun Ultra 5 to learn Sparc Solaris at home.. A couple of desktops converted over to rack mount cases and racked in a cheap telecom rack in my unfinished basement. This was very early in my career when I had a lot to learn and plenty of free time to study. However that was many moons ago.
SAN
Much Todo About Linux/RHEL Passwords
My latest gig requires me to know more about passwords, password expiration, and password policies than I have ever had to know before. Now on the surface this is a bad thing, as it makes my job much harder as I have to maintain more passwords on more individual systems than I can shake a … Continue reading Much Todo About Linux/RHEL Passwords
Recovering from failed vxevac
If you have ever evacuated disks in Veritas, every so often this will happen to hang. Usually you terminate your session or who knows what. Kinda like Joe Girardi's willingness to sacrifice outs for no good reason every time the Yankees hottest hitter is at the plate. It happens, you can't explain it, you move … Continue reading Recovering from failed vxevac
Resolving SCSI Reservation Conflicts/Locks in Vsphere 4.0
A few days ago we got hit with a ton of alerts which indicated that a handful of VMs were down, then up, and down again. This cycle continued several times. At first, after a bit of digging through logs, we thought that the issue was related to scsi reservation errors, but we were already … Continue reading Resolving SCSI Reservation Conflicts/Locks in Vsphere 4.0
Veritas Enterprise Administrator Not Displaying Objects/Agents
Its been a while since I have done much with Veritas Storage Foundation, so I was at a bit of a loss after firing up the VEA gui on a fresh install on Centos 5.4, and not seeing any of the agents that I was used to seeing. A quick check on the command line … Continue reading Veritas Enterprise Administrator Not Displaying Objects/Agents
Raid Levels Explained and Simplified
First off its important to know that RAID stands for either "Redundant Array of Independent Disks", or more commonly "Redundant Array of Inexpensive Disks". Either way you slice it (pun intended) the basic idea of RAID is to combine multiple hard disks to either increase performance or increase redundancy.
Before I get started its important to introduce the term LUN. A LUN is a logical disk that consists of raw physical disk space. LUNs are created as a basic part of the storage provisioning process. They are presented across a SAN to a server as a single physical disk.
Note that the title of this article is "Raid Levels Explained and Simplified", and when I say Simplified I mean it. I am going to give a brief overview of most of the common RAID levels and then present a weakness and strength.
Linux SAN Disk Managment via DM-Multipath
A little background... Most of the time, I have used the RDAC driver in Linux to manage SAN disks in Linux. The RDAC driver is used to hide the complexity of multiple paths and to present redundant paths as a single path which can be used as you would a standard SCSI / IDE / … Continue reading Linux SAN Disk Managment via DM-Multipath