Opinions from experience - RAID 0 vs separate disks

Jimbo Mahoney

Jimbo Mahoney

Jimbo Mahoney

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I'll soon have 2 x 150GB Raptors.

Now, traditionally, I've always used two drives in my PC - one for the OS and one for the Swap and programs (swap at the start of the drive in its own small partition to get maximum transfer speeds and prevent fragmentation / make defrag easier).

I currently use a 36GB Raptor as my OS drive and a 200GB 7.2k disk as my games / apps drive. These are both getting long in the tooth and have fairly low transfer speeds (~55MB/sec) and high seek times.

My primary use is gaming, overclocking and benching, there will be no irreplaceable data on this machine - it is almost entirely expendable as it's purely a gaming / clocking rig.

I'm almost sure to do a test with both configurations, but I'd be intrigued to hear from people who have tried both options - two drives as one RAID 0 volume, giving higher transfer rates vs. two separate drives giving independent disk usage to the OS and the games / swap.

OS will be Vista 64, 4GB RAM. RAID would be motherboard RAID, not separate card.

If I do go RAID 0, given my planned usage, would my best bet to optimise performance be to analyse the files on the disk using JDiskReport and choose a Stripe size accordingly? e.g. say my most common file size is ~ 64kB, then my best Stripe size should be 32kB when using two disks?

EDIT - [LittleBritainCarol]Anandtech says no.[/LittleBritainCarol] Anandtech reckons largest stripe size available, so 128kB typically.

My gut tells me that RAID 0 would create a faster system, given that I am really only doing one thing at a time (e.g. booting OS, then benching, then playing a game)...

EDIT 2 - I've decided not to bother with RAID 0 as the overwhelming real-world evidence of reducing level loads, as well as analysis of my drives' typical files size, all point to around 1% speed increases.

64kB Stripe:

http://www.anandtech.com/storage/showdoc.aspx?i=2969&p=8

128kB Stripe, Raptors:

http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=10

Analyse your drives' file sizes to help determine stripe size:

http://www.jgoodies.com/freeware/jdiskreport/index.html
 
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Pandobear said:
Regarding stripe size, I don't have the answer, opinion seems to reflect that bigger stripe sizes are better for large files, small for small files. i am not sure that I understand this, as I would have thought that this relates more to the formated block size over the hardware stripe size.
Click to expand...

I would assume it's because the file gets split into the stripe size before getting written to disk using the cluster size.
 
Thanks for the feedback. There's some useful tips there.

I've done some analysis of my C Drive (OS) and E drive (games - mainly Steam and WoW) and it came up with surprisingly small files:

C Drive - 80% of files are <64kB, 62% are <16kB

E Drive - 85% of files are <64kB, 72% are <16kB

This means that choosing a stripe size of 64kB or larger will only benefit ~15 - 20% of files!

C Drive - most common file size is 1 - 4kB

E Drive - most common file size is 4 - 16kB

From this data, I would be inclined to go with 8kB, 16kB or 32kB stripe size.

EDIT - What's the smallest stripe size ICH10 offers?
 
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Can you create various volumes with different stripe sizes?

That way, I could have the OS with a 8kB stripe and the games with a 16kB stripe...

EDIT - Man, I'm really pouring my brain straight onto here whilst reading about RAID at the same time. Too small stripes = too much overhead, making seek time a limiting factor.

Given my drives' content, I'm thinking that RAID 0 is not going to offer much performance at all. The files are pretty small and in order to get any benefit from RAID 0, the stripe size is going to be 1/2 the typical file size, meaning even smaller, which means I'm going to be seek-limited anyway. If my files were consistently 512kB+, I can see the benefit, but with so many files around 16kB or less...

After all this, I think I'm going to stick to two separate drives.

More proof here:

http://www.anandtech.com/storage/showdoc.aspx?i=2969&p=8

(64kB Stripe size)
 
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da_ging said:
yes on the ich10 you can create more than 1 raid volume with different strips

i've got a 100GB for windows at 32KB strip and the other 1100odd GB at 128KB strip for everything else

I am somewhat curious that your games drive reports so many small files as mine only has 3.1% under 256KB

and my C: drive only has 2.7% under 64KB , are you sure read it right?
Click to expand...

Are you sure you've read yours right?

Make sure you look at the % of files, not % of total. (Although I suppose we could argue which is a better measure of the correct stripe size...)

Also, remember to sum, e.g. On my laptop drive, 15% are 0-1kB, 12% are 1kB-4kB, 18% are 4kB-16kB, 20% are 16kB-64kB, thus it can be said that 65% of files are under 64kB in size.
 
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