RAID 0 vs 1

Question

I have always heard that RAID 0 is for performance and RAID 1 is for reliability, but it may not be as clear cut as that.

I read in a Adaptec Controller manual that RAID 1 offers an increased performance (compared to a single drive) when reading data because it can read the data in stripes from both drives at once (just because your file is on both drives in full does not mean it has to read the entire thing from one drive while the other spins idle). Write performance for RAID 1 is no better (perhaps even slightly worse) then the slower of the two drives in your array.

I was wondering if anyone knew if the SATA RAID controller build into the motherboard of the 8400 and XPS was sophisticated enough to read RAID 1 arrays in stripes? I noticed that Dell does not even offer the 10,000k drive in a RAID 1 option.

Does anyone know of a good benchmark comparing the XPS with a single drive, RAID 0 and RAID 1?

SteveP55419 · Answer

Hi,   Well, I just finished installing RAID on my 8400. I was conflicted just like you until I did a little research on my own. It turns out that the Intel SATA controller and comes with the 8400 will let you set up 2 RAIDs on one RAID array. I have 2 Seagate 160s in the array. For the first RAID, I created a 50 GB RAID-1. Then I created a RAID-0 for the balance of the HD space which amounted to roughly 200 GB. This is a best of both worlds setup. I have my OS and important data on the redundant (RAID-1) RAID and easily replaced stuff on the RAID-0 RAID. Because I chose to put the OS on the redundant RAID, I gave up some of the speed advantages of the RAID-0 since the first RAID you create gets the outside tracks of the disk and the OS has to go on the first RAID. But that's OK since I was really looking for redundancy in the first place and this lets me have it without halving all of my HD space. Intel says that you will see a performance benefit from the RAID-1 as well as the RAID-0 and my experience bears that out.   Here is an interesting discussion and walkthrough of this technology: http://www.gamepc.com/labs/view_content.asp?id=matrixraid&page=1.   Steve

ejn63 · Answer

RAID0 is striping without parity.

RAID1 is mirroring

RAID5 is a combination - striping with parity (redundancy).

RAID0 offers the best performance, but poorest data integrity. RAID1 offers the lowest performance (slower than a single drive, actually) but best data integrity. RAID5 is a compromise - better performance than RAID1, better data integrity than RAID0.

SteveP55419 · Answer

Sorry about that. For some reason, I thought you were talking about an 8400 system.

nyhunter · Answer

thanks for some vital info.

sphbecker · Answer

To say RAID 1 is all about redundancy and not performance is a bit of a misnomer. It is correct for writing, because data must be written to both drives at the same time. On the other hand, when it comes to reading a RAID 1 should provide better performance then a single drive.

This is because pieces of the data is on both drives (just like in RAID 0). Let’s say you want to see blocks 1-6 in a sector. RAID 0 would read blocks 1,3 and 5 from one drive and 2, 4 and 6 from the other. Well, guess what? RAID 1 can do the same thing! The only difference is that with RAID 0 blocks 1, 3 and 5 are continuous but with RAID 1 it must skip over 2 and 4 to do the read the others.

Now that is the theory. I was wondering if anyone knows of some benchmark tests to show the read performance improvements of RAID 1. My guess is that when reading data RAID 0 is the fastest and RAID 1 is somewhere between it and a single drive; for writing data I would assume that RAID 1 and single drive are about tied with RAID 0 far ahead.

SteveP55419 · Answer

You might check this out: http://www.neoseeker.com/Articles/Hardware/Features/intelmatrixich6r/4.html.

sphbecker · Answer

I am not too big of a fan of Intel's Matrix array just because it requires two logical partitions, but the more I think about it the more I think about the more sense it makes. The only real down side is that your free space is split into two different pools, but with today’s big drives that is almost a non-issue.

My plan will be to get an XPS with two 150 GB drives (I'm hoping they have a 10,000rpm 150 GB drive by the time I order). I will use the Matrix option to create one 100 GB RAID 1 array and another 100 GB RAID 0 array. I will then put/reinstall the OS along with all my important data on the RAID 1. I will install all my software, games and move the system PAGE file to the RAID 0. The RAID 0 area will also be a really nice place to work with large video files.

Storage, Drives & Media

RAID 0 vs 1

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