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RAID 0 or RAID 5?. Please help me.

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January 16, 2007 11:19:38 AM

Hi guys. I have 3 HDs Western Digital 250GB SATA2 16MB and I use some type of RAID. But I have a problem, I don´t know what RAID Level is better.

I have two options:
1.- RAID 0 using 2x250gb and I can use my 3st HD for backup manually some important files.
2.- RAID 5 using 3x250gb.

What´s better? what RAID is more fast?

Sorry for my english, and thanks in advance.

More about : raid raid

January 16, 2007 11:56:30 AM

RAID 0 is faster without a doubt, unfortunately, if one of your drives fail, you lose the entire array. It's a pretty risky thing to use as a result, and tbh I don't think the performance gains are great enough to be worth that risk.

RAID 5 on the other hand does make sense in some situations. You do lose the storage capacity of one drive, but it can tolerate losing a single disk, so you have data security. The downside though is that whilst read performance is good, write performance suffers. Also the overhead of doing software RAID 5 can be pretty high.
January 16, 2007 12:15:48 PM

One option you would have is to stripe Drives 1+2 into a RAID 0 array for max performance. (Not Highly Noticable but still max performance.)

Then leave Drive 3 out of the raid and use it to make backup of Data files from Drives 1+2.

I'm not a big fan of Raid for home systsms for a number of reasons.

Here is a simple one - Let imagine in 3 years your Mobo goes up on flames. There is a good chance that a replacement Mobo will not have the same raid hardware and the 3 drives may not be readable. For Companies this is not an issue since they usually have hot spares sitting by, similar servers to swap drives in temporarily, and they use product lines designed to be support over long periods of time.

Imagine software issue with the RAID, bad Bios update, etc.. etcc.. etc..

RAID 0 I really dont like due to added chance of failure. I would rather split duties on the HDD such as Progarms on one and Swap on anotehr to speed performance.

RAID 5 will give you redundancy and would not be a bad choice if you are not likely to keep your system files backed off to the 3rd HDD as the possible idea I suggested.
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January 16, 2007 1:38:32 PM

Raid 5 offers good performance with added reliability, while raid 0 offers performance. raid 0 will be faster but I doubt you will notice THAT much of a boost over raid 5.
Raid 0 can also be done with 2 drives, while Raid 5 requires 3 minimum. keep in mind they have to be identical for it to work properly, or the array will be as fast as the slowest drive, and as small as the smallest drive. ALSO, Raid 0 can be done with 3 drives as well if the controller can support it, just an option. :D 
As a side note, everyone talks about reliability. I have ran a Raid 0 array with two of the 36gig Raptors for around 5 years with no problems. the redundancy of a raid array will only help with mechanical failure, or the off chance of a hiccup somewhere in the line (data corruption due to bad information). it will NOT help against viruses, messed up drivers, registry or stupidity. it all boils down to personal preference.
In addition, Zen is correct (learned this the hard way) that with a mobo swap, if the controller is different, the array stands a good chance of needing to be rebuilt. solveable with a 3rd party controller, but why bother with a free one that is built in? again personal preference. This imho will make the Raid 0 with the 3rd drive as b/u a much more tempting to me. good luck!
January 16, 2007 2:25:04 PM

Quote:
In addition, Zen is correct (learned this the hard way) that with a mobo swap, if the controller is different, the array stands a good chance of needing to be rebuilt. solveable with a 3rd party controller, but why bother with a free one that is built in? again personal preference. This imho will make the Raid 0 with the 3rd drive as b/u a much more tempting to me. good luck!


That's why I'd scale back on the motherboard a bit and drop in an add-in RAID card. Consider the free portion of the builtin card and then consider the mess it involves when you swap out the board (looks like you found out personally). That add-in card looks pretty nice when that happens.
January 16, 2007 2:55:39 PM

But that is still only a partial coverage.
You will need to buy 2 of the controllers (in case one fails) and still have not safety for accidentally deleted files and/or a corrupted file system since as mentioned the Raid only helps with mechnical failures.

At this point backups to Tape and/or DVDs is not really feasible so this should be planned.

w/o another "Server" of some type to cross backup files this needs to be planned for.

I'm a real data safety freak.
My Laptops and Desktop backup to my home server.
My Home Server backups from one HDD to Another.

I know this is an "Enthusiast" website and many folks would chop off their arm for 1fps or a 1sec load time increase. Myself, I'm more in the Nascar mentality. I love speed but if/when all heck breaks loose, I know I'm walking away w/o a scratch.
January 16, 2007 3:02:34 PM

Quote:
What´s better? what RAID is more fast?

Raid 0

OK, thats done. :lol: 

But seriously, put two drives in raid 0. Use the third drive for backup.
January 16, 2007 3:19:22 PM

unless your raid controller is a pure hardware controller that has a xor processor just do raid 0 other wise performance will suck on a raid 5 array.
January 16, 2007 3:44:21 PM

Very thanks for all the answers. Definitely I will go for RAID 0 and I will use my 3rd drive for backup.

Thanks again!!
January 16, 2007 4:22:29 PM

Try Intel's Matrix Storage technology. You'll get both RAID 0 performance and RAID 1 redundancy. Yes, you can have it with as little as two hard drives.
January 18, 2007 3:28:27 PM

Quote:
unless your raid controller is a pure hardware controller that has a xor processor just do raid 0 other wise performance will suck on a raid 5 array.
Quote:


lcdguy hit the nail on the head, with raid 5 you do have some overhead,especially without a dedicated XOR processor, plus raid is still no substitute for regular backups. Go RAID 0 and(if you use windows) have windows do an automated backup every night and have the best of both worlds.
January 19, 2007 12:37:15 AM

Quote:
Quote:
unless your raid controller is a pure hardware controller that has a xor processor just do raid 0 other wise performance will suck on a raid 5 array.

lcdguy hit the nail on the head, with raid 5 you do have some overhead,especially without a dedicated XOR processor, plus raid is still no substitute for regular backups. Go RAID 0 and(if you use windows) have windows do an automated backup every night and have the best of both worlds.


Yup. Your question really amounts to....

Do I want to accept really bad reliability or really bad performance?

RAID 0 is faster, but your data is spread across the drives so that all data is lost if even 1 drive fails. RAID 5, on the other hand, uses parity to protect the data but that parity had to be calcuated by the CPU (slowing the system down) unless you have a dedicated controlled with an XOR processor.

Why not get 4 drives and run them as RAID 10 (0 + 1) so that you get good performance and reliability? You lose half your capacity that way, but drives are relatively cheap these days.
January 19, 2007 2:49:02 PM

Ok, flame me if you will, but I have read every 2-drive RAID 0 benchtest out there and all the experts seem to think that due to increased seek-times, RAID 0 will give you NO noticeable difference in performance at all if you are dealing with multiple small files (e.g. loading a game), but will give to 20-30% performance boost if you are dealing with single large files, and either way half your time-to-failure with the addition of no redundancy.

So surely before you recommend this poster that he should go RAID 0, should we not ask exactly what he intends to use this array for? Also, unless you are using a Raptor array, all of the benchtests suggest that 1 x Raptor will at very least equal any 2-drive RAID 0 array for performance in any type of application, suggesting that the answer is to sell the 2 drives on ebay and buy 1 Raptor right? Or as the previous poster suggests, go 4 drives.
January 19, 2007 3:18:46 PM

I have to agree with zenmaster here. I've been researching setting up a a 4 or 5 disk RAID 5 setup for my media files, since I want a TB or two of storage and I'd like to not have to backup the data on DVD since that would be reams of disks. Once you're up at 4 or 5 drives, the percentage capacity hit you take from RAID 5 is less, since it's still only one drive.

However, I had to consider one simple fact. In my time, I've never lost a HDD. I've known people who have, but it hasn't been a terribly common experience. On the other hand, I've burned at least two motherboards. It seems to me that as long as Mobo's are less reliable than HDD's, then there's not much point to worrying about setting up a RAID 5, or any security RAID for that matter on a home system, unless you also buy a second identical motherboard or RAID card and keep it in storage.

No... when I do build my media server, I'll be using a file system that allows dynamic adding and subtracting of drives to a given volume. Modern file systems can bring you some RAID-like performance/security features without the hassle of using RAID. Downside is I don't think you can use Windows with such file systems. Microsoft is slowly learning to play better with friends, but it's painfully slow. Linux makes more sense for a file server anyway.

For the OP: I believe the consensus is that if you want performance HDD, then the best bet is to get a good 10K (or even 15K are available now) RPM drive, along with a standard 7.2K drive for file storage.
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