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RAID 5 or 10

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March 9, 2010 1:39:39 PM

Alright, before I get in over my head I wanted to make sure I'm going in the correct direction... I am building a new web design/photo editing computer, all parts have been ordered. I'm using 4x Western Digital Caviar Black WD1001FALS 1TB 7200 RPM drives.

Since this computer is primarily for web design and photo editing, is a RAID 10 array the best way to go? Or would I better off with RAID 5? What are your thoughts or suggestions?

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March 9, 2010 5:23:51 PM

Bueller?... Bueller?... Bueller? :bounce: 
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a c 415 G Storage
March 9, 2010 8:38:50 PM

RAID 5 has very poor write performance and generally speaking provides less protection for your data than RAID 1. I'd personally go with RAID 1 myself. ...well no, that's not true - I don't actually bother with RAID myself.

Remember that you still need to do backups. If you don't have any external drives to make backups to then I'd take two of those drives, put them into external USB 3.0 enclosures, and use them for alternating weekly backups.

That's the reason I don't bother with RAID. I don't worry about drive failures (which in 25+ years of personal computer use I've never had) because if I ever have one I can just restore from a backup.
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March 9, 2010 8:46:33 PM

I do understand that RAID is not backup. :)  I actually already have weekly backups taken care of.

So for redundancy, wouldn't I be better off sticking with RAID 10?
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a c 415 G Storage
March 9, 2010 10:26:41 PM

RAID 1+0 will certainly give you redundancy, potentially better transfer rates (depending on the type of I/O your applications do) and good read/write performance even if you loose a drive.
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a b G Storage
March 10, 2010 10:37:39 AM

I'm not sure I agree that raid 5 offers less data protection than RAID 1. Both (as well as raid 10) give you some short term protection against HD failure. All RAID levels can impact your drive throughput - usually for the better. How they do, for what types of reads & writes, with what kind of software, isn't always straightforward.

For another thread, I mentioned that RAID 10 is highly recommended for DB work. I'm sure it will do well for other uses as well, but I don't have experience with them.

How disk-intensive is web design? Photo editing, I can see being a little more disk intensive for something like heavy photoshop use, but I'd think RAM is more important there to prevent swapping.

So 1 or 5 might suffice to give you some redundancy, at a reasonable cost, and some performance benefit. 10 would give you more performance, at a higher cost.
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a c 415 G Storage
March 10, 2010 9:43:10 PM

gtvr said:
I'm not sure I agree that raid 5 offers less data protection than RAID 1.
The more disks you have in a RAID 5 set, the more risk there is to your data, whereas with RAID 1 the more disks you have, the more secure your data is (most people only use two disks in RAID 1, but you can have more if the controller supports it).

The problem is that with RAID 5, if you loose a disk the only way you can recover your data is to successfully read EVERY sector from EVERY other drive. If you have an unreadable sector, you're hooped. And with unrecoverable read errors occurring typically once for every 10^14 bits read, that means there's about a 1 in 10 chance of getting an unrecoverable read error when you try to read every sector from a 1TB drive. So if you have a RAID 5 volume with 6 1TB drives and one of them fails, you have a 50% chance of not being able to recover the data successfully by retrieving it from the other 5 drives. Even for a 3-volume RAID-5 set with 1TB drives, there's something like a 20% chance that the data can't be recovered, twice as high as for a 2-volume RAID 1 set. With a 3-volume RAID 1 set, there's almost an ironclad guarantee that the data can be recovered since it's extremely unlikely that you'll get unrecoverable read errors at the same sector of both of the mirrored copies.

So that's why I say that generally RAID 1 is a little more robust in terms of data protection than RAID 5.
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a b G Storage
March 11, 2010 10:33:36 AM

Ah, you've been reading zdnet.

RAID 6 then, if you're really paranoid. 8)
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March 11, 2010 1:13:15 PM

Best answer selected by scrappy77.
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