Tuesday, September 09, 2008

iSCSI - nice solution

Prior Events

I like my Linux Notebook. I really do. I started to dual boot Suse Linux back in 2002, I set it up as primary OS in 2003, I removed dual booting in 2005, using some virtualization solution or the other for things that required Windows. By the way, during these years, I saw less and less needs to do that.
During these time, as professional, I bought several notebooks (If I remeber correctly, about five notbeooks from 2001 to 2008). In these times, when I was to change my notebook, the old one would be used by my wife in our home network.
Well, let me say that - it was a pain, getting back to 2000/XP to fix things, with all the cycle of installation, maintenance and antivirus.
These year, i asked to my wife if she were willing to try a Mac. Shock and horror, but less shock than a windows machine in my house. Also, I am attracted to Mac OS X. I admit that.
So this MacBook ended in our home, and my wife is using that mainly by herself. No maintenance required.

Backup, backup, always backup

I am quite fearful to lose my digital data. Projects, documentation, invoices, mails, mostly reside on thin slices of metal with some magnetic coating... scratching heads hanging over them with only microns of thin air. Scary, indeed? It's your hard disk.
So, for the macbook, the solution in Leopard was... time machine. Quite ambitious as a backup application, indeed easy to setup and use.
One drawback: only directly attached (firewire and USB) disks, or the Apple time capsule. See, a year ago I ended up aquiring this NAS device (Freecom FSG-3 250 GB, wireless) which, altough useful, i found somewhat limited.
Anyway, i could back to this NAS with some hacking, which was not recomended. In the meantime, i replaced the FSG-3 with a dual desktop abaco computer ( Abaco ) . So now I have this full featured x86 dual core low power machine. I began thinking again of the backup over the network with time machine.

What I did

Initialize Time Machine

First step, was to take the USB disk i was willing to use as a backup unit, partition it, and format as a HFSplus file system. HFSplus is the Mac OS X journaled file system, think ext3. On this unit, attached via USB, i started to use Time Machine through the control panel. This way, first backup is done locally, probably faster than on the network.

Install iSCSI TargetiSCSI target is the Server machine which exports file systems and / or devices. A client uses an iSCSI Initiator to connect to a target. When connected, the device is seen as a local device, with all defaults options available. Exposing a target is a simple three line configuration file:
Target iqn.yyyy-MM.domain.name:uniqueidentifier
Lun 0 Path=/dev/sdc,Type=fileio
Alias MacLacie

Test iSCSI
Before going further in the iSCSI path I checked the configuration installing the Linux Initiator on my machine. After some fiddling with the console, a sudden iscsi start opened a nautilus connection with the content of remote, iSCSI attached disk. Server was working.

MacOS side
I was under the impression that Leopard had a native iSCSI initiator, but that is not the case. I downloaded and installed the free (but not open source) globalSAN iSCSI Initiator from studio network solutions

Reconfigure Time Machine
You can attach the iSCSI device through the control panel applet in System Preferences. After that, the device is sensed and usable from Time Machine. Backup through wireless of a delta (around 600 MB) then took around ten minutes. Not bad.

What I have to do

  • Hal rules rewrite the device is seen as /dev/sdc through HAL. I have to rewrite some rules to force device location (cannot use UUID for device...)

  • Services check Shut down the machine and restart - everything should work ok
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