HTPC RAID suggestions

[corwin]

OK, so I just picked up 3 1tb HD's planning to do a RAID 5 install in my HTPC only to realize that my MB only supports 0/1/10....from my research the only real benefit of 10 is less performance degradation in the event of a drive failure, since this is only a HTPC I'm not as concerned about that, just about not losing my data. So I started looking at cards and can't believe how expensive some of them are...so I guess I am looking for some thoughts on my best options. Would a PCI version limit the throughput dramatically or stay with PCIe? The drives are sataII but would a sataI card be sufficient? How about sataI and PCI? Or if the cards are going to be over $100 would it be better to just buck up and buy another drive?

I should add that the hosted files are DVD and Blu-Ray ISO's primarily....

 

[Knavish]

-- If you're using linux for your htpc, you can use software raid.

-- Max 32bit / 33mhz PCI bandwidth is 132 MB/s, shared between all PCI devices. There will be some overhead for card, so you won't get all of this for your disk transfer speed. If all you got on the PCI bus is a RAID card, this would probably be enough for your HTPC. If you're sharing the PCI bus among TV tuner(s), network, sound, etc, this could be a bottleneck.

 

[corwin]

No on the linux....only a wireless card would be sharing the PCI bus...and I would guess on a PCI connection sataII wouldn't help much.

 

[taltamir]

raid5 on mobo is TERRIBLE and should NEVER be used.
your research also is wrong.
Raid 1 is a mirror, you have 2 drives containing the same data. So writing is as slow as the slower drive (which, if identical, it is identical), and reading is an addition of the speed of the two drives (so, if identical, its twice as fast). If either drive is lost, no big deal. And you can easily transfer it.
Raid 0 is a stripe, you split the data equally between the two drives, so reading is twice as fast, and writing is also twice as fast. You also don't "waste" any space. but if EITHER drive fails the data on BOTH is lost...
Raid 1+0 means making a mirror of raid0 arrays. So you can have 4 drives, drive A and B are a raid0 array1, and drive C and D are a raid0 array2, and array3 is a raid1 array of array1 and array2. It gives you data safety while greatly increasing your speed (4x the read speed of one drive, 2x the write speed of one drive).

RAID5 is for people who are trying to save money on drives, it splits the data between all but one drive, and then it calculates a parity that it palces on an additional last drive. To write data you have to first calculate the parity for that particular data. The more drives, the more complex, and slower the process is. Writing to a raid5 array can be EXTREMELY slow, a fraction of your total write speed of one drive... or if it has a dedicated quality controller (at least 300$ controller) it can be extremely fast.
Reading from RAID5 is as fast as a multiple of the amount of stripes you have. aka, if you have 2 data drives and 1 parity drives you read from 2 drives at once, and the speed is 2x of one drive.

 

[taltamir]

ps: buying another drive and doing raid10 will greatly increase your performance comapred to raid5 cheap controller... and it will be much cheaper than buying a quality 300$+ controller.
If your motherboard HAD allowed raid5, you would have faced data storage so slow that the quality of your intended use (HTPC) would have suffered... that is, until you lost all your data.

if you are looking for SAFE, than do two seperate RAID1 arrays, so you will have "drive C" which is a raid1 array of 1TB (2x1TB drives), and drive D which is a raid1 array of 1TB (2x1TB drives).

 

[Binky]

Why not 2GB of Raid 1 in the machine, and 2GB of NAS storage anywhere in the house? Sounds like your data security doesn't require up to the minute backups. Nightly auto-sync would work fine.

 

[corwin]

First the debate over performance of RAID 10 vs RAID 5 is wide and varied, but I have never seen a claim of 4x read improvement....and the performance hit for RAID 5 comes in the writing while calculating the parity bit, not much of an issue for HTPC, but the read is the same as a striped array as the parity bit has nothing to do with it on read. It's not so much the cost of the drive that's the issue but the heat of another drive in the enclosure. I am planning to do a NAS but haven't decided on one yet, might just take my chances on a RAID 0 setup now and focus on getting a NAS for backups

 

[Blain]

Originally posted by: Binky
Why not 2GB of Raid 1 in the machine, and 2GB of NAS storage anywhere in the house? Sounds like your data security doesn't require up to the minute backups. Nightly auto-sync would work fine.

He couldn't hold much content at all with that plan. :roll:
Plus, the drives would be very hard to track down.

 

[Binky]

Originally posted by: Blain
He couldn't hold much content at all with that plan. :roll:
Plus, the drives would be very hard to track down.

Lol, you know I meant to say 2TB!


I installed one of these for my HTPC about a month ago. Works great so far. Raid 0 or 1 couldn't be easier. Probably not upgradable beyond 2TB. Slightly noisy.
http://www.newegg.com/Product/...x?Item=N82E16822101080

 

[corwin]

Not a bad looking enclosure, but not a NAS either, it requires a PC....