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I'm running a small IT company. Specifically less than 10 persons all are developers and no system administrator. I am so to say the owner doing much of work. So now I am asking the question being a system adminstrator at this specific moment :)

Recently we bought an intel's SR1690WBR and two HDDs WD1002FBYS. I did not know what was a FAKE RAID. And it turned out the the server system we bought had one onboard (ICH10R). So I decided to buy a real hardware RAID controller. My budget is $200 and I am looking at the Adaptec 1405 http://www.adaptec.com/en-US/products/Controllers/Hardware/sas/entry/ASC-1405/.

So my question is: looking at the price of the RAID controller 1405 and at the price of the HDD doubts crept in me that installing this RAID could degrade our server's performance in some. I think so because I am not a system administrator, I just know more than basics. I understand that we will have fault tolerance with the help of RAID 1 but can I possibly loose any performance in such a configuration?

Thank you.

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3 Answers

up vote 3 down vote accepted

The product you linked is a HBA, not a raid controller. "Series 1 non-RAID Unified Serial HBAs offer economical I/O with broad device compatibility, scalability, and flexibility for servers, storage, and backup applications"

But to answer you question in a more general matter: Yes, RAID can give you a performance penalty, depending on wich RAID level you want to use.

You mentioned RAID1 as your choice of raid level, wich is quite the excellent choice when it comes to a OS array or any other array where you don't need a ton of disk space. It has zero penalty on write performance (it writes the same data to both disks as it would have been with a single disk), but it has a quite major performance benefit on read speeds since it can read data in paralell from both disks (in a nutshell, read half the file from each disk if the file isnt uber-small).

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Great answer pauska - I'd also add that Adaptec's RAID 3405 (adaptec.com/en-US/products/Controllers/Hardware/sata/value/…) would be an excellent R1 choice and shouldn't cost too much more. –  Chopper3 Oct 4 '10 at 7:34
    
Good answer. Raid contorllers start at the 2xxx series, the 1xxx is a pure HBA. I wouldsuggest giung with a 5805QZ for strategic purposes. Btw, SuperMicro has NICE cages with up to 72 disc slots in a 4 rack unit configuration that work nicely with it. –  TomTom Oct 4 '10 at 7:54
    
Pauska, thanks. Again I did not fully understand that 1405 is NOT a RAID controller. Sorry, guys I understand that this is offtopic already, but as usual everything comes to money. We cannot afford a RAID controller for more than $200. What can you say about Promise Fasttrak tx4310 for a backoffice server for developing purposes? –  Grigory Oct 4 '10 at 8:15
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The only thing I can say about Promise is that they are good at releasing new products, and then shortly after abadoning all support and driver maintenance for it. I guess it's what the nice price tag stands for. –  pauska Oct 4 '10 at 8:18
    
Man, this tx4310 seems to be a fake raid. Seems like we have to make some more money and buy a real hw RAID controller like Adaptec 3405. Anyway, thanks. –  Grigory Oct 4 '10 at 8:20
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Grigory, RAID 1 can cause some minor performance degradation due the face that most controllers wont consider disk-writes done until both disks are done. This means that if one disk is taking a bit longer for a particular write operation then the entire operation will take longer. The speedloss is usually insignificant and what you gain from redundancy overcomes it :) Just don't forget real backups too...

Short answer is: You, as a human, won't notice any difference, if on the other hand you'r running a highend server with 1000+ users, then you might notice some minor differences...

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Not a performance degradation from software raid normally. –  TomTom Oct 4 '10 at 7:55
    
@TomTom, write performance on software R1 arrays is routinely slower than via hardware R1 due to bus saturation as the OS has to write the data twice to the controller unlike a hardware solution. I'd be interested in any data you have counter to this. –  Chopper3 Oct 4 '10 at 8:12
    
Theoriteically. Practically two crappy hard discs will not saturate anything in a real server scneario - way not enouh IOPS budget to saturate a modern bus. –  TomTom Oct 4 '10 at 9:48
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To answer: Yes, it can, but it would be called either broken hardware or bad drivers. Make sure you invest wisely - not something that brings nothing, Paying pays off here. Ad then get some decent discs if needed.

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