12.04 Server Raid

[mobo]

I have up and running and Ubuntu 12.04 LTS Server with lamp hosting four sites at the moment and soon to be adding more. I would like to add a measure of reliability besides weekly backups of Databases and the www folder.

I have never dealt with a raid configuration before so please excuse my ignorance. Can I make this sever a raid server now that it is up and running? Will the raid ensure that if a drive goes down that the server will still operate fully (OS & all its files)?

[PowerBarry43]

Hi

I am certain that you can switch an installed server to raid but off the top of my head I don't know how, you may have to create the array and then move your installation into it, as far as added reliability goes, you probably want to have raid 1.

Raid level 0 would give you the combined space of two or more drives as one drive

Raid level 1 is mirroring or a running backup, where you have a pair of drives in the array and they are always identical with regard to their data. This would allow one drive to die without the server going down, in other words total redundancy.

Raid Level 5 is parity, if you've not heard this term before it basically means you have 3 or more drives and one of the is used to store data that is generated based on the data in the other two allowing you to rebuild a drives data based on knowing the method used to generate this extra data and knowing the result of this process. For example you have two drives that contain "4" and "6" respectively you add them up to get "10" store that in a third drive then drive two dies... you know you have "4" and what was lost must addd to "10" therefore you know whats missing is "6" this is more or less what raid 5 does.

Hope this helps!

Barry

[mobo]

Thanks Barry..Raid 1 is what i'm looking for..Now just the howto...

[ali abry]

Thanks Barry..Raid 1 is what i'm looking for..Now just the howto...

this is for year 2009 idon't now if things changed :
http://ubuntuforums.org/showthread.php?t=1832812

[mobo]

Loks like we're going to find out if 12.04 is workable...I have a backup server here already to go that will be a good sacrificial machine for the test..Thanks for the link and check back later for the verdict..

[rubylaser]

Why don't you test the process with a virtualbox vm rather than taking the risk on an untested process?

[mobo]

Well its only a server that I built to work out any kinks that may present themselves before building my main server. Its just sitting there unused..Its basically identical to Server 1 so this would be a great way to see if I would run into any issues with the main server...I'll be starting in a few hours when I can have dedicated time..

[mobo]

You know, after looking at the entire process, I may be the wiser to update the databases on the backup server to match server 1 and put that back online and do server 1 over in raid 1..

Why? Becuase it looks like it may be easier to do than convert.

[wlraider70]

The program you want establish the raid array is mdadm.

you can google a guide pretty easy. this post is old but very detailed.
http://ubuntuforums.org/showthread.php?t=408461

The most important thing to know is that the server will have to come down and be booted off a live disk to that you can tell the 2 drives to copy each other.



As for just making the second server an exact copy you can use rsync to make a folder copy itself to a destination. You should be able to do this from the live server to the backup server. I'm not sure how you would make the backup server take over from the live server automatically, but I'm sure there is a way.

[mobo]

Hey thanks for the Link...Its sure is a good read. I'm at a bit of a stand still right now after considering what I wanted to do ( Webserver & Samba file server for home media) so I ordered a couple of terabyte sata drives, more memory and some cat 6 cables to have a setup that is both relatively up to date as well as redundancy that I need.