The best RAID setup for my situation?

kaotik123

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Hi guys got some questions.
New to RAID, but I am tech savvy.

Ok basically I have a media centre with 3x3tb Hdds. They are all installed as seperate drives (not RAID) and filled with data.
I want to set them up as RAID but as I understand this will wipe the data on the discs.

So if I buy an NAS box and another 3x3tb hdds on a RAID setup, can I transfer the data from the media centre to the NAS, and then RAID the existing 3tb hdd inside the media centre and then transfer the data in the NAS back? I guess I am asking is this best way to go about this?

What RAID type would be the best for the NAS and media centre?

Thanks in advance :)
 

dingo07

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It's probably the fastest way to go about it, other than buying 3 separate drives and transferring the data one drive at a time

A RAID 5 is suggested, but I suggest you use a minimum of 5 drives including a hot spare
 

dingo07

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The minimum number of drives to implement a RAID 5 is 3. Should one of those drives fail, depending on the software/hardware controlling the array, the data will be available as degraded or not available until a new drive in installed and the data is rebuilt.

I suggest five drives because some controllers offer a "hot spare" which makes drive 4 available immediately should drive 1-3 fail, which means there's less of a hassle to rebuild the data while operating as degraded. That then leaves you the 5th drive to install where the drive failed, which brings you back to a fully operational scenario.
 

kaotik123

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Hmm ok I think I understand now (after a lot of reading :))

Since this new NAS that I am buying will only be used to transfer the files back and forth one time (even though I will probably keep a copy of my data on the NAS anyway as a backup), would you recommend setting up a RAID 0 or a JBOD array? (therefore still only using 3x3tb and getting a 9tb total capacity) as data security/failure probably wont be as much as an issue with a one time transfer?
 
The Raid format has nothing to do with the number of transfers. With a Raid0 all your data is gone, if one disk fails! With JBOD you will loose the files stored on the failing disk only. With Raid5 you will loose nothing, if only one disk fails.
 

kaotik123

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Ok thanks for your reply.
Hypothetically speaking, is it possible to have say 4 drives setup in RAID 5 configuration and then 2 hard drives not included in the RAID but just normal independent drives? So in 'My Computer' they will show up as 3 separate drive letters (with one of the drive letters containing the 4xhdd RAID setup)?
 
Which level of RAID to go for depends on what your goals are, and the purpose of the NAS.

If its going to be a streaming device, possibly streaming multiple users HD footage, then you would want as much performance as you can. In this case a RAID0 or RAID10 would be best.
If its essentially a place to backup your machines and store media with no real demanding load placed on it, then you would want a RAID1 or again RAID10 array.
RAID 5 and 6 IMO isn't really all that useful for the home user, though if you have enough drives it can be a better option than RAID1/0/10 as its more efficient with drive capacities once you ahve enough drives and offers redundancy. However your write performance will suffer in 5 and 6.

Or just keep it simple and stick with the JBOD.

EDIT: Depends on the NAS tower your getting, but I imagine it will allow you to only set up some drives in a RAID array.
 

Yes.
 

kaotik123

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Ok I have actually decided against the NAS now.
What I plan to do is install another 3X3tb hdd into my computer (making it a total of 6 drives inside)
The new 3tb HDD will be setup in a RAID and the remaining drives will stay as they are for now. So this is possible to do this? My motherboard is a P8H67-M. This guy: http://www.youtube.com/watch?v=RrS4vZZVcDg seems to think that if you have to setup a RAID for every single connected drive and you cant just choose which drives you want to put in the RAID. I will be doing a software RAID.
 
It will depend on your motherboard what RAID options you have.
If your doing RAID from the motherboard, dont try 5 and 6 even if it is supported. Due to fact that those levels of RAID require calculations to do correctly, this adds a constant load to the CPU and will slow down write performance significantly. If you want RAID5/6, you need a dedicated RAID card.

You should be able to set up only certain drives in RAID arrays, while keeping others as JBOD or even a different array.

From my understanding software RAID is not as good as a hardware RAID, though not all that knowledgeable in this area.
 

kaotik123

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Hmm ok then.
Well I will buy a RAID controller card then and setup RAID 5...
So now I can install the card, connect the new 3x3tb hdds to it. And then have 4 drive letters show up in my computer (1 drive letter is the new raid setup and the other 3 letters are just the existing separate drives)?
EDIT: My motherboard is actually a Asus P8Z68-M Pro
 

dingo07

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drewhoo

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Kaotik, I think I am in a very similar situation to yours, but a few purchases ahead.

If you're going to have 6 3tb drives in your box anyway, you might consider a raid50/raid 5+0. It's a RAID0 striped over two 3-drive RAID5 arrays, OR a RAID5 comprised of 3 2-drive RAID 0 arrays.

Six drives is the minimum for RAID5, and the first setup provides fault tolerance for 2 drives (as long as those two drives are in different sub-arrays). You can only do it with true hardware controllers (read: $400+ cards) and it is supposed to give better performance than RAID5, though I have a very difficult time pinning down performance numbers on RAID5 since there are a staggering number of variables to sift through.

I just recently got 6 1TB HDDs and a 3ware 9750-8i with the intention of setting up RAID5 or RAID50. Over the next week, I'll be benchmarking various setups to see what suits me best, and I'd be happy to share the results with you if you think it might inform your purchase.
 

kaotik123

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Yes I think its best to get a dedicated controller card.
I am confused as to which one to get though. Some are $50 and some are $500, some have batteries and others dont, some are full hardware and others rely on software. After hours of research I think I am more confused now than I was when I started lol. Can anyone recommend a good card for around $100-$150??
@dongi07 - Thanks for the suggestion. However I think eventually I will be connecting all 6 drives up to the array so need a card that will support this.
@drewhoo - Thanks I would love to hear the results of your tests. Would be much appreciated. Wow, that card is over $500.
 

drewhoo

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That highpoint card only does software raid--that's why it is priced so low. It will do fine for any RAID level that does not include calculating parity information (0, 1, 1+0). If you run a RAID5 with that card, it will use processor cycles to calculate parity information (read: it would be slow). So buying that card is the equivalent of slapping 8 6Gb/s SATA ports on your motherboard 1) without adding any hardware to control it 2) to take away bandwidth from your other PCIe device (I'm assuming it's a gpu).

I also found the RAID controller market very confusing. Customer reviews are less reliable, I think, because the technology is more esoteric and used for more varied purposes than a processor or more basic component.

To answer a few of your questions: you can get a hardware raid controller for $300 - $400 that controls 4 drives. A hardware RAID controller is going to have specs for its RoC (Raid on Chip) as well as cache specs (which the Highpoint card lacked because it's a software card, though Highpoint does make true hardware raid controllers--they're priced like everyone else's).

You get a BBU for a hardware RAID card because it has a cache (that acts like RAM) that it uses to write information to the array. If the power goes out and there's stuff in the cache, it's gone forever. My understanding of the BBU is that you do not need a BBU if you have a UPS. However, the UPS does not protect your data from your dog getting her leg wrapped around your computer's power cord and unplugging your computer from the UPS. The BBU will sit inside your box for 72 hours (on full charge at least) holding onto the cache data for you until you can restore power and write the cache data to your array. I just got a UPS and kicked my dog out of my study.

So I eventually just picked four equivalent cards and then looked around each manufacturer's website to compare the documentation and support services they provide. I liked the 3ware card best because it has really thorough and clear documentation.

Also, you should consider what drives you're using for RAID5. The major threat to RAID5 data security is not a dual drive failure (RAID5 can tolerate 1 drive failure, but you lose all of your data if 2 drives fail) but rather an Unrecoverable Read Error (URE) while rebuilding after a drive fails.

--the following argument is based on this really helpful article that examines the exact setup that you're considering: http://www.standalone-sysadmin.com/blog/2012/08/i-come-not-to-praise-raid-5/

If a drive fails in your RAID5 and you replace it, your controller must read the (3TB worth) parity info of the remaining drives in order to write it to the new drive. Consumer (even WD Black) drives have a URE rate of 1 in 1e14 (this is usually found on the manufacturer's website), which means that you can read a full 3TB HDD about 3 times before it is extremely likely that you will have a URE. So when rebuilding (and reading) there is a much better chance than you would like that you will have a URE and your data goes splat.

That said, enterprise drives have URE rates of 1 in 1e15 (that's almost 40 reads for a full 3TB drive). Of course these are more expensive, and some "enterprise" drives still have URE rates of 1 in 1e14--make sure you check the manufacturer's specs.

These are the low URE rate drives that I got: http://www.newegg.com/Product/Product.aspx?Item=N82E16822149449

WD's RE4's have low URE, and so do Seagate's ES.3's

edit: here is what crystaldiskmark told me about my 5 disk raid5 setup with the 9750-8i on toshiba MG03ACA100's: http://i.imgur.com/WOnvaxn.png
 

dingo07

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while all of that ^^^ is very useful information- the OP distinctly said he wanted a suggestion on the price point of $100-$150 - what I suggested was $9.99 over his budget

You can't get hardware raid for less than $450 in a good card. Case in point (like I stated previously about suggesting an Adaptec card) - here's what I would get IF I wanted to implement RAID 5 - http://www.newegg.com/Product/Product.aspx?Item=N82E16816103099
and that's the least expensive card I would get
 

drewhoo

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Yeah! And your answer is perfect for that price point. I felt the need to elaborate because kaotik expressed his frustration with understanding the card market. Also, I am unsure about the benefit of a software RAID card other than a shortage of motherboard SATA ports. What is the downside to using motherboard ports if you have enough?
 

drewhoo

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Maybe I didn't pose my question as clearly as I could've. My question is, what is the difference between running a software raid off of your motherboard's controller and running a software raid off of a dedicated pci/e card? If Kaotik has the ports to run the raid off of his motherboard, why would he buy a $150 software raid card?
 

kaotik123

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Ok yes I was very confused about the RAID controllers. And thanks drewhoo for clearing that up, was very informative.
I thought it might be possible to get a full hardware RAID card for around $150 but its clear now I will have to pay more as I dont want my CPU to handle the RAID calculations and slow my system down. I will need extra sata ports anyway as I have nearly run out. Thanks for the recommendations dingo.

Sorry for changing my mind so much throughout this thread, it was all very new to me so wasn't sure what would work best.

So RAID 5 is likely to be very slow even with a dedicated card? And RAID 6 similar performance?
 

dingo07

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First, let's leave RAID 6 out of the equation. What do you mean by slow? If you mean rebuild time for 6TB of data, then yeah - it'll take some time.

The bottom line is - if you care about your data and it's integrity (not losing it) then you spend the money for excellent hardware, both the controller and the drives to minimize the pain should a drive fail.

Tom's review of the Adaptec 5805 card (a little dated) - http://www.tomshardware.com/reviews/adaptec-serial-controllers,1806.html