FalconNL

Question about RAID 5

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Hello,

I'm researching my next computer and today I stumbled upon this forum. My current computer used RAID 0 up until the second harddisk crash. Needless to say I won't be using RAID 0 anymore (or Maxtor disks for that matter). My search for alternative had led me to RAID 5, which combined the ability to suffer a harddisk failure with a low overhead, i.e. lower cost. However, today I learned about the low write performance of RAID 5. The data is slightly conflicting though, with some people recommending RAID 1 for the OS partition and other saying there's little noticeable difference in performance.

So my question is as follows: Will the performance penalty of RAID 5 be noticeable on a home computer or is it merely a problem for database servers and the like?

The components will be:

P965 motherboard, like Asus P5B Deluxe/Wifi or MSI P965 Platinum

5x 320 GB disks, probably Seagate Barracuda 7200.10 ST3320620AS or Western Digital Caviar SE16 WD3200KS

The computer will be used for:

- Graphics applications like Photoshop and 3D Studio Max

- Recent games

- Bittorrent (current connection speed 3 Mbit down/512 Kbit up, typical usage about 5 files of 300MB-4GB simultaneously)

- Other daily use stuff like internet, Office, etc.

In case that using only a RAID 5 is not advisable, is it possible to have both a RAID 1 OS disk and a RAID 5 data array on the motherboard RAID controller or is a separate controller required?

Thanks for the help.

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Hello,

I'm researching my next computer and today I stumbled upon this forum. My current computer used RAID 0 up until the second harddisk crash. Needless to say I won't be using RAID 0 anymore (or Maxtor disks for that matter). My search for alternative had led me to RAID 5, which combined the ability to suffer a harddisk failure with a low overhead, i.e. lower cost. However, today I learned about the low write performance of RAID 5. The data is slightly conflicting though, with some people recommending RAID 1 for the OS partition and other saying there's little noticeable difference in performance.

So my question is as follows: Will the performance penalty of RAID 5 be noticeable on a home computer or is it merely a problem for database servers and the like?

The components will be:

P965 motherboard, like Asus P5B Deluxe/Wifi or MSI P965 Platinum

5x 320 GB disks, probably Seagate Barracuda 7200.10 ST3320620AS or Western Digital Caviar SE16 WD3200KS

The computer will be used for:

- Graphics applications like Photoshop and 3D Studio Max

- Recent games

- Bittorrent (current connection speed 3 Mbit down/512 Kbit up, typical usage about 5 files of 300MB-4GB simultaneously)

- Other daily use stuff like internet, Office, etc.

In case that using only a RAID 5 is not advisable, is it possible to have both a RAID 1 OS disk and a RAID 5 data array on the motherboard RAID controller or is a separate controller required?

Thanks for the help.

In my opinion, if you're not planning on spending enough money to get a decent high-end RAID controller, you shouldn't even consider RAID 5 for either a desktop or a server, particularly if write performance is at all important for your applications.

Personally, I think that if you're looking for performance and are willing to spend some money for it that RAID 1+0 offers higher performance than RAID 5 that comes close to straight RAID 0 performance while offering a high degree of protection from drive failure (which RAID 0 lacks).

I also believe that decent RAID 1+0 controllers can be had for much less than high performance RAID 5 cards.

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The problem with raid 1/10 is that is quite expensive. I'm looking for around 1 TB of effective storage, which would mean 8 harddisks. This would mean buying a separate RAID controller (assuming there are varieties that support 8 cards) and upgrading from a miditower to a full tower. Alternatively I would have to use bigger capacity disks, which have a higher price per gig than the 320 GB ones.

While I'm by no means building a budget system (estimated price of 1600-1800 euros without monitors), the extra 400-500 euro I would have to spend is a tad much. I also prefer a miditower over a full tower.

So the question was not whether RAID 10 would be faster (I know it is), but if RAID 5 can be used without too much noticeable slowdown on the hardware mentioned, as it appears to be the cheapest solution (450-500 euro for the disks + about 150 for the motherboard = 600 euro for 1280 gigs of effective storage)

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Run a regurlar backup to be put on an extra drive. of course this means you would only be backing just the essentials you can't afford to lose.

You could get much lower performing, thus lower cost backup drives for this purpose.

backing up the OS is of little utility because you can do a repair installation and have your system up in not much time.

RAID5 or better 5E, 5EE is quite fast, little penalty on a hardware based RAID adapter.

Cheap insurance is to make sure your drives have dedicated cooling fans pushing air over them.

Some ideas here to help you think things over

JB

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Yeah, after the second crash I bought a 250 gig external harddrive for backups. The idea of RAID is to save me from having to re-install everything.

What is the speed difference between the raid controller in the Southbridge and a real 100-200 euro RAID card?

Also, are there any recent benchmarks on things like southbridge vs hardware RAID 5 or a comparison between different RAID levels on the same harddisks? I have so far been unable to find them.

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You would only need 4 hard drives for 1TB effective storage in RAID 0+1 or 1+0.

And there will also be a slowdown but how much is really up to how you see and use it.

Photoshop and 3D Studio don't write a lot in themselves, but they do use a lot of memory - that can result in lots of thrashing of the pagefile and of the scratch disk. Both of these will be majorly slowed down with RAID5, you might wanna get a seperate (~80-160gb) drive for just that. As far as games and Bittorrent goes, you won't notice much of a difference, and it might even be faster.

There isn't much difference between southbridge RAID and 100-200 euro RAID cards, since 100-200 euro RAID cards are el-cheapo software ones anyway, and thus pretty much identical to the one on the southbridge - slow.

You'd have to look at 300+ euros to get a proper, "hardware" RAID card.

Edited by qasdfdsaq

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If Photoshop performance would indeed be the only thing really affected I think I'll go for the RAID 5, as pretty much all of my PS documents should be able to fit in the 2 gigs of RAM the computer will have.

A look at the different options gave me this:

RAID 5: 4x 320 GB Seagate Barracuda 7200.10 ST3320620AS  = 360 euro for 960 GB (2,67 GB/euro)
RAID 5: 4x 320 GB Western Digital Caviar SE WD3200KS	 = 396 euro for 960 GB (2,42 GB/euro)

RAID 5: 5x 320 GB Seagate Barracuda 7200.10 ST3320620AS  = 450 euro for 1280 GB (2,84 GB/euro)
RAID 5: 5x 320 GB Western Digital Caviar SE WD3200KS	 = 495 euro for 1280 GB (2,59 GB/euro)

RAID 10: 6x 320 GB Seagate Barracuda 7200.10 ST3320620AS = 540 euro for 960 GB (1,78 GB/euro)
RAID 10: 6x 320 GB Western Digital Caviar SE WD3200KS	= 594 euro for 960 GB (1,61 GB/euro)

RAID 10: 4x 400 GB Seagate Barracuda 7200.10 ST3400620AS = 516 euro for 800 GB (1,55 GB/euro)
RAID 10: 4x 400 GB Samsung SpinPoint T133 HD401LJ		= 476 euro for 800 GB (1,68 GB/euro)

It's hard to ignore RAID 5 being so much cheaper.

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RAID 5 won't be cheaper if you get a good RAID controller. Meaning an add-in PCI or PCIe card with enough RAM of it's own. Think upwards of €500.

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I would suggest a pair of 80gb drives in raid 1 for boot, with 4x 500gb in raid 10 for your data.

The only way to do raid 5 and to make it actually work properly is to have a PCIe or PCI-X raid card, which it sounds like you don't want to spend the money on.

Ideally I would suggest you buy an 8 port PCIe raid card, it will work on the second PCIe slot on the P5B Deluxe motherboard, and buy 4x 500gb drives to start off with and configure them in Raid 5, in the future you can add drives to it as you need. Areca, Promise, LSI, even Intel make good PCIe 8 port Raid 5 cards.

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Yeah, a 300+ euro RAID card is out of the question since for that money I can simply go for the RAID 10 array, which is faster and more secure. Oh well, RAID 10 it is then I guess. Let's hope prices go down a bit in the next couple months.

Thanks for the help everyone.

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