SAN

Linux Fibre Channel SCSI Target using SCST

Fibre channel or Fiber Channel is also another way to present SCSI devices over a network medium using a complete different protocol suite then my previous article on iSCSI. With Fiber Channel transfer speeds and protocol delivery is much faster than iSCSI. The fundamental difference between the two is iSCSI uses TCP/IP protocol suite to deliver SCSI messages, and Fiber Channel uses Fiber channel to deliver SCSI message. This means that you will have to have network equipment that is Fiber Channel capable, such as Fiber Channel switches, Fiber Channel HBA (similar to TCP/IP NICs), etc. For the purposes of this article I will not go into how Fiber Channel works, or how it does it’s job of delivering SCSI messages two and from SCSI initiators and SCSI targets. This article will step through how to turn a Linux machine into a Fiber channel SCSI Target. There are a few things you will need to even attempt this:

  • A Linux machine running Kernel 3.2+
  • SCST and SCSTAdmin (see below steps)
  • A separate machine that will act as a Fiber channel initiator, this can be another Linux machine, or an ESX host, etc
  • At least two(2) Fiber channel HBA’s with one physical WWN port each installed in both machines
  • A OM2 or 3 Multi-mode Fiber cable with connectors capable of being used with the HBAs
  • Enough disk space to create a Virtual Disk so we may present it as a LUN
  • And lastly, some excitement!! you are about to enter the new world of Fiber Channel!!

Continue reading…

Linux — dd Operations Notes

I recently was helping a friend with some computer trouble which resulting in me first creating a full disk Image backup using “dd”. I’ve done this before years ago, but I wanted to add some of the common dd backup/restore methods to my notepad. There are so many articles online on how to use dd to do a Full disk backup and restore it. I will be using similar methods.

dd Terms

  • if — input device (file,hardware,CD,etc).
  • of — output device (file,hardware,CD,etc).
  • bs — sets “dd” read and write size.
  • noerror — continues after read errors.
  • readom — CD to ISO utility.
  • mount — Linux command to mount file-systems
  • gz — gunzip is a compression utility which helps to reduce the size of images created with dd.
  • md5sum — a checksum utility to ensure integrity when moving large image files.

Continue reading…

Linux — iSCSI Target using open-iscsi

I recently set up an iSCSI SAN for use with VMWare Server. The set up was basically a Linux Ubuntu Server target with 2 network links to a single VNWare Server as the integrator. I also included iSCSI multi-pathing by enabling it on the initiator (VMWare Server).

This is how I set up an Linux SAN Target with iSCSI, interfacing with VMWare 5.1. as the iSCSI Initiator.

Continue reading…

Linux — Recovering from Drive Failure with mdadm

So it happened. I had a drive fail on me. Degrading my RAID 6 media server. Luckily I was notified by mdadm and was able to order a new one from newegg.com and rebuild it.

I want to walk through the steps I took getting my RAID file system backup and running, starting with the notification I received to my gmail account (which i received on my phone).

Continue reading…