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How do you manage RAID migration and repair?

Last response: in Storage
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January 15, 2011 6:04:11 PM

I've been doing some searching and I can't seem to find a good breakdown of how this all works. OK, I'm pretty new to the idea of running my own NAS so if any of this is blatantly obvious please forgive me.

To give people a quick run-down on what I'm planning, I currently have just a 2TB hard drive that's quickly filling. I want to go RAID so I can make my data redundant. I also want to increase the total usable capacity so right now I'm looking at doing at least a 4-disk array. Either RAID5 or RAID10, I haven't decided which. I get the impression that RAID5 has higher capacity but there are some reliability issues? I'd love someone to explain that to me as well...

Anyway, the key point of this post is this: Let's say I successfully build myself a 4-disk RAID array. Let's say it's a RAID10 because I'm hearing that might be the best way to go at this point. If I had 4x2TB drives and wanted to upgraded to 4x3TB drives, how would I have to go about that? I've heard one option is a backup and basically rebuilding it from scratch and replacing it with the backup but I really don't want to have to go that far. I would like to be able to do this all from within one machine for now.

Other than expanding the individual drives, what i fI wanted to go from a 4x2TB RAID10 array to a 6x2TB RAID10 array, would it be possible to add the two new drives to the array without rebuilding it from scratch?

Basically, I'm trying to figure out the basic points of managing a NAS RAID array so I can decide whether it's in my best interests to either just buy something like a Drobo (expensive and lean on features but so easy a child could use it) or buy an NAS or build my own.

I'd also love to know if any one OS makes it easier than any other OS. So, basically, I'm open to any and all suggestions.
January 19, 2011 8:11:44 AM

Newcomer, probably the best place to start for an overview of raid and the meanings of the different levels is to go to Wikipedia- http://en.wikipedia.org/wiki/RAID. With any raid array you need to choose a point between maximum data redundancy and maximum data read/write speed. At its simplest this is a choice between raid 0 and raid 1. Raid 0 is essentially making an automatic copy of all the data it stores whereas as Raid 1 essentially allows you to read and write to 2 discs at once (assuming a two drive setup). Also available are Raid levels 2, 3, 4, 5, 6. As a starting point raid 0 will give you a disk usage efficiency of 50%, the other levels of raid will give you higher efficiency.

There are three basic ways to install a raid system, the first is a system controlled by Windows, the second is a system controlled by a motherboard chip and the last is a full hardware controller via a PCE slot. These various controllers have different limitations in relation to your Raid migration and repair. I would suggest it is also worth considering which of these three systems will be best for you in the event of an array failure.

In my case I recently purchased a new flatscreen TV which was probably a big mistake because there is very little in the way of high-definition content which led me to start saving is much high-definition content as I could on my network and upscaling many of the DVDs I already had. It took next to no time to plough through the space on the six drives I had on the network.

The other problem I had was the insanity of many of the name vendor's to either not fully support DLNA or not fully support all file types commonly in use today. My solution to kill two birds with one stone was to add another PC with a Windows 7, Raid 0 array to the network which you could describe as an NAS with VLC media player installed connected directly to the TV.

Hope this helps and I'm sorry I couldn't link the wiki page but only because I can't find any controls on this page to link but you can copy and paste.
January 19, 2011 1:54:16 PM

No worries, your reply was pretty helpful.

That's pretty much what I've learned so far. Right now, I'm leaning towards RAID10 because I've heard it can perform a bit better and doesn't take as long to repair.

The problem is there are certain things I can't seem to find. For example, I can't seem to find the process to upgrading my RAID configuration from smaller drives to bigger drives, whether that's for a software, hybrid or hardware RAID. I tried looking for specific systems like Ubuntu's server edition but I couldn't find any information there.

It is one of the biggest things holding me back from diving in and starting to fully pick out my hardware. Once I get it I still don't know how to run it and if I'm going to be spending a few hundred dollars as a minimum I'd like to know the process each time I need to repair or expand my RAID.

The one thing that gets me so far is I'm hearing that the only way might be to have another server that I can back up the first server to which would allow me to rebuild the other server with higher-capacity drives. I know in terms of data protection this is best but it would also be a lot more expensive than I plan on spending at this time.

Dunno, more to think about.
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