Review my RAID plans please

Ofc you can, like any aspect of computers there are high end (usually enthusiast/business class) controllers and daughterboards for high end applications. Onboard motherboard RAID is usually reasonably good, but too limited and software based for a lot of high demand applications, this is where the specialist hardware comes in (much like Audio/Video equipment), which tends to cost more because of A) Specialisation B) Lower volume made and sold.

This used to be more common than it is now, nowadays a lot of the standard raid functions can be handled by decent home motherboards, but there are still applications where a high end dedicated card is necessary :)

When you can spend £200+ on a card 'just to produce sound', is it that unbelievable you can get spend £400 on a card which controls the spanning of mutiple discs and data sectors to form one large drive system?
 
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AWBbox said:
I have done a little reading on dmraid after what you said and it looks like people have been succeeding with it after kernel 2.6.24 I have tried this method in the past without success which is why I discounted it as an option in the first place. I might have to give it another go! Also, how come those Perc 5/i controllers are so cheap?? I am amazed actually, they seem to have all the functionality I need except they are a fifth of the price of the 3ware RAID controllers.

  • I do regular backups onto a separate drive which is then kept off site. I didn't see that the redundancy of RAID5 would bring any benefit. Plus, the performance difference between that and the RAID0 I am used to looked awful on paper.
  • I have no more free SATA ports on my motherboard, they're all used up. I want more hard drive space, and I guess at a push I could run to 4 free 3.5" bays.
Click to expand...

Hey,
I enjoy linux, but occasionally use CAD software which ties me to windows. That's a strong argument against raid 5, but its also quite a strong argument against raid 10. Does frequent backups not suggest raid 0 across all the drives is a better call?
I definitely feel your pain at running out of sata ports. The cheaper raid card is a good solution.

That card is so much cheaper because it doesn't have a processor on it, and wont have the large amounts of quick memory the more expensive ones supply. This matters for raid 5, and it matters a lot if you strap cacheless ssds to it, but for raid 10 just isn't important.



I take it there is a raid 0 of raptors involved? I assume there must be but cant see where you said so. If so, then raid 5 will be slower. How much this matters for a non-os drive is hard to determine.

This reminds me of why I didn't use raid 10 in the first place (I bought 4 drives intending to). The internet seemed pretty sure that a two disk raid 0 of samsung f1 drives would kill a raptor for performance [and that 4 disk raid 10 = two disk raid 0]
I didn't want to risk this asymetry, so I went with the slower option. If you raid 0 the storage drives, its quite possible that they'll be quicker than the raptors your os is on. That would drive me mad, but you might not mind.

If there's a single raptor involved, a 4 disk raid 0 is very likely to flatten it.

I'd trust the linux ntfs support a hell of a lot more than Id trust windows to treat ext2 competently. One thought is that if windows is just games, do you need access to the entire raid array while gaming? I decided to run ext2 on the array, and not let windows see it. ext2 and mdadm is about as stable and easy to manage as anyone could ask for, and windows can't randomly break my data if it can't see it.
 
I just thought I would post an update on what's been going on. Thanks to Zarf's recommendation I have gone ahead and bought a (Dell) LSI Perc 5/i RAID controller from a popular auction site. It was a little over £100 for an 8 port SAS RAID controller with 256Mb of memory (expandable to 512Mb), two in-line 4 way SATA cables and a battery backup unit. After reading up a whole lot in a thread on this forum, it seems I can even firmware it to be (to all intents and purposes) exactly like the board it is derived from, the LSI MegaRAID SAS 8480E. And those things still retail at £500-£600 :eek:

Anyway, it should arive in 7-10 days or so and I will update when I have more to report. I won't be able to afford the hard drives for at least 3 weeks anyway.

Edit: Also, forgot to mention I have been convinced into using RAID 5. Those benchmarks on the forum I linked to aren't too shabby at all!
 
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You might need a PCI plate too, they are usually on the auction site, though i just scavenged one from an old vga card i had.
 
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