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Extending RAID5

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a b G Storage
November 16, 2012 2:45:48 PM

OK, so the simple question is:

On a z77 motherboard (ASRock z77 extreme4) will the onboard Intel RAID support the ability to extend a RAID5 array (by adding a 4th drive) without loosing data?



Now for the details on what has gotten me to this point:
Last year when I did my system rebuild I got an Extreme3 gen3 motherboard which has RAID functionality. Over the course of the year I ended up with 2 240GB SSDs, and the temptation to set them up in RAID0 was simply too great, so I did it, and my inner nerd was very happy (until the lack of TRIM functionality adversely affected writes). But as RAID was enabled I grabbed a 2nd 1TB HDD that I had laying around and mirrored the 1TB drive that I already had in the system. As the drives were dissimilar (same brand, but 4 years apart) performance went to hell, but due to the unstable nature of the RAID0 I wanted something redundant for a backup. Lo and behold, 5 months after I set up the 1TB RAID1 array I suffered a drive failure. Ends up the failure was on the part of the older drive I added to the system, but it was still a learning experience on how to fix the issue, which went relatively straight forward, and I did not lose anything. Fast forward to last month and I replaced the mobo with a newer z77 Extreme4 mobo in order to support TRIM over RAID0 for my system drive. I was happy to notice that I simply enabled the RAID controller and it recognized my drive configuration instantly. No muss, no fuss, and I was really happy that my write speeds came back on my SSDs.

The problem I face now is that the drive I replaced the failed 1TB drive with is on loan from a friend, and, well, he frankly needs his drive back soon.

So the long term thought is to go with a RAID5 with 4 2TB drives, and the setup would look something like this:
Intel, SATA3 -> RAID0 2x 240GB SSDs
Intel, SATA2 -> RAID5 4x 2TB HDDs
other, SATA3 -> BluRay drive and case eSATA header or considering getting a removable drive bay for doing data backup

The issue is that I simply cannot spend the money for 4 reliable 2TB drives right now. I could stretch for 3, but then I am going to have to wait a while on the 4th as I have some other issues that need money thrown at them right now. So the thought is to get 3 drives now, start using it, and then add the 4th drive later. I know that there are a lot of actual RAID cards which allow for this functionality... but as that would be overkill for my situation (not about to spend $500+ on a good RAID card), I am wondering if the onboard RAID controller will allow for this type of functionality without loosing any data.

I am also annoyed that the prices have not dropped further! Just over a year ago you could get a 2TB drive with a 3-5 year warranty for $80-100 each, and they were rock solid on performance and reliability. A flood and a year later you can get a 2TB drive with 1 year warranty, terrible reliability reviews, and it is going to cost $100+. Or else you can get a relatively reliable 2TB drive for ~$180ea. Sure I did not complain about the premium I paid for my SSDs... but they are performance drives! These simply need to be big and reliable... grr

Anywho; I just don't want to jump onto this new HDD platform, move all of my data to it, rip all of my movies and disc images to it, only to have to repeat the whole process all over again 6 months down the line when I have some 'spare' money to play with again. Any advice would be greatly appreciated!

More about : extending raid5

a b G Storage
November 16, 2012 5:22:23 PM

You won't loose your data. The RAID5 will expand across the 4th drive, keeping the data intact. What is not clear about the z77 boards is whether RAID expansion is in the background or foreground. Background expansion allows you to use the RAID array while the RAID rebuilds (albeit with very slow access). With foreground, the RAID array is not accessible until the rebuild completes. A rebuild of your size will take hours or even days depending on the use of your system.

Another challenge will be for your OS to use the new space on the RAID. You will need to verify if you current file system supports resizing and whether that option is available online or offline.
a b G Storage
November 16, 2012 7:32:42 PM

You won't loose your data! <- No there is always a chance you will loose your data.

Expand RAID volume is VERY tedious and longtime. During the expansion you can have a corrupt data if power is disrupted.

If your data is important - BACK IT UP before any attempt.
a b G Storage
November 17, 2012 10:35:16 AM

Thanks! That is what I was hoping to hear!

@firewire2
Yes, I always keep 3 copies of the important documents (local, hot copy on another machine, and a web copy). It was more an issue of if loss-less expansion was possible because the process of ripping all my DVDs and BluRays seems like a monumental task that I would rather do only once if at all possible. Even if the expansion process takes multiple days to complete it would still be worth a try as I can just leave the machine on to do it's thing during that time rather than having to babysit each disc going through the ripping process a 2nd time.

@Nothing But NAS
the file system is currently NTFS (good 'ol Windows default). Last I checked you can do partition re-sizing with it... or is that not what you are talking about?
!