Author Topic: Setting up RAID on a hybrid system for main system disk?  (Read 2592 times)

jmcrtp

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Setting up RAID on a hybrid system for main system disk?
« on: May 21, 2008, 08:23:48 pm »
Is it possible to do this after you have installed LinuxMCE?  I found a few threads showing to install Ubuntu with software raid on two disks, then install LinuxMCE on top.  I have MCE installed on a 1TB disk and I would like to mirror that with a second 1TB disk for fault tolerance.  I hope this is possible without reinstalling, but if not do I just need to get the CD download, the Ubuntu CD, and install ubuntu with raid, then mce on top? 

Currently I can go into the config menu but it allows me to configure raid on two new disks.  If it is possible to do this in the KDE environment outside of the MCE admin page I'd be happy to do that.  I would like to avoid reinstalling since I have the setup working great and it has taken a while to get it here.

Thanks for any assistance!

Jay Armstrong

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Re: Setting up RAID on a hybrid system for main system disk?
« Reply #1 on: May 23, 2008, 03:59:27 am »
This is possible but perhaps tricky. You'll be using mdadm from the command line and the general steps would go like this:

1. define your current partitions as raid devices
2. define your RAID array as raid1 and tell it that your second drive has "failed" (not exactly true, but it won't remember in the morning)
3. start the rebuilding process, where mdadm will see your spare drive as a new replacement for its raid1 array and will begin copying your contents to the new drive.

In the end, you'll have all of your partitions replicated on each drive except for the boot partition. This means that if the physical drive that has your boot partition dies, you won't be able to boot your system, but you still won't have lost any data. Alternatively, you can copy your boot partition onto a second drive, but it doesn't provide a seamless boot failover: you would need to manually edit GRUB to direct its boot to the backup drive.

It's been a while since I've done it, otherwise I'd give you more detail. This is a decent resource:
http://gentoo-wiki.com/HOWTO_Gentoo_Install_on_Software_RAID

Practice it once or twice in a virtual machine and you should have no problems. If you do decide to reinstall, you can get the k/ubuntu alternate CDs, which set it all up for you with a little fiddling in the partitioning section.

GLHF

PS. I may be doing this myself in a couple of weeks so please post back any good finds.


deffcon

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Re: Setting up RAID on a hybrid system for main system disk?
« Reply #2 on: July 09, 2008, 12:27:29 pm »
Hi All,

I planning to follow this guide http://www.debian-administration.org/articles/238 , but can some explain the partition scheme from the amd64 double layer dvd?


Thanx

Dave

jondecker76

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Re: Setting up RAID on a hybrid system for main system disk?
« Reply #3 on: July 09, 2008, 01:03:17 pm »
Having a redundant system disk is overkill in LinuxMCE. You would be much better off just having a single system disk, then a raided media disk(s). If your system disk ever crashes, just reinstall LMCE - most all of the database information is stored in .id3 tags in the media filesystem now, which makes restoring your database pretty easy. Raid protection in this case is much better off on the media side of things. (IMO)

deffcon

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Re: Setting up RAID on a hybrid system for main system disk?
« Reply #4 on: July 09, 2008, 01:44:16 pm »
Hi,

So you are implying that all my settings all my symbolic links etc, most off all my total config, just reinstall, no way, there is a lot to be done after the double layer installation has been completed. I want it redundant, and i don think its an overkill, can someone please explain why there has been chosen for an /dev/sda2            8271        9730    11721969    f W95 Ext'd (LBA)
I'm following above tutorial and i really think it can be done, when i finished it all i'll wikifi it all.

Dave