craigr

Thanks for all the great information and links guys. I really appreciate it. Based on the fact that it seems that having a faster parity drive will not increase the speed of parity checks, I will likely not pursue the idea of a RAID 0 for the parity drive. I wish there were a way to increase the speed of parity checks. craigr

One thing is that I already have two LSI 9211-8I and 8x SATA ports on my MB. So I'm not too worried about an extra SATA port taken by two parity drives. Why don't you think parity check will be any faster? This is one of the primary reasons why I liked the idea. I was under the impression that unRAID reads from all data drives simultaneously during a parity check. And as such, having a faster parity drive to compare with would increase speed. What am I missing? I would really like to improve parity check times. Thanks again, craigr

I use the server pretty hard which is why I am concerned with unRAID at all really. With FreeBSD I can easily saturate my network with writes to the server, and the server isn't the bottleneck. I don't think the 3TB drives would be a good choice to repurpose for RAID 0 parity because they are WD Green 5400 RPM drives. So they would be about the slowest possible RAID 0 cache possible craigr

Thanks for all the info. Do you happen to have any old links to the tests or threads? I already own the 3TB drives and they are installed in my FreeBSD server now. I need to buy 4x4TB drives for data so that I can transfer all the data on the FreeBSD server to the unRAID server. I will than need a 4TB drive for parity. This could be another 4TB drive or it could be two 2TB drives in RAID 0. Either way, I have to buy new drives for parity so it can be either 2TB drives or 4TB drives. It sounds like you think the performance increase with 2x 2TB drives in RAID 0 will be nill though. I am thinking that I will probably use a 256Gig SSD drive for cache so I won't need another array for that. craigr

I don't think there is any physical difference between the green and red drives other than the color of the sticker. It seems the only real difference is the firmware that WD uses to control the hardware. I think WD just adds another year of warranty for marketing the drives at a higher price. The reds don't park their heads every 8 seconds, but with the greens you can disable head parking to achieve the same result. The reds to support TLER which the greens do not. Those are just my observations that I can't prove other than by what I have seen. craigr

Hey Steven, In looking at your signature again you have: So were you using two 4TB drives for 8TB of parity? Why didn't you use two 2TB drives? I would like to use two 2TB drives as the two drives together in RAID 0 should sum to 4TB which is the same size as my largest data drive. Thanks for any more info. craigr

But looking at your signature Steven, it seems that you are running a RAID 0 parity drive (or at least you have done so in the past). craigr

Yes, I realize that all drives are equally important. My point, which perhaps was not completely clear, is that you'll be rebuilding parity following a failed drive replacement more frequently and that increases the chances for encountering a drive failure while the array is not protected by parity which could lead to data loss. I understand that if either of the drives in a parity RAID 0 array dies that you will loose your parity data. I said that I understood that risk in my original post. That being said, unRAID retains all the data on all the data drives even if the parity drive(s) die. So all one needs to do is replace the failed drive in the parity array and then rebuild the parity drive if a parity drive failure ever occurs. Of course if you also happen to be very unlucky and lose a data drive while the parity array is down than you will lose the data on the dead data drive. I consider that unlikely and even if it happens it's no big deal because it's just one drive with BD rips on it that I can always recreate if necessary. So I guess you could say that I honestly don't value the data all that much so I am willing to tolerate more risk to increase write speeds and parity checks. craigr

That is 100% incorrect! I ran an ARC-1210 with two 4TB Hitachi's on it for about a year. Configured a 4TB RAID0 for Parity and a 1TB RAID1 for Cache. I worked beautifully! I got great speeds. I removed the Areca card when I reconfigured my server recently. However, I may go back to this configuration. Wait, so are you saying that what I want to do will work and you have done it? I'm the OP and I want to run two 2TB drives in RAID 0 as the parity drive for a server that has 4TB data drives. I'm confused because it sound like you are saying that my idea will work, but you quoted Thornwood when he said that he does not think it will work and it seemed like you were saying he is 100% correct. I don't see how unRAID would know if I have a single disc parity or a RAID 0 for parity so I don't see how it wouldn't work really, but I just want to be sure. I have used unRAID just for testing so I have little experience with the OS. I have been running FreeBSD for years. Thanks, craigr

I am building a new unRAID server and I am wondering if it would be possible to use two hard drives in RAID 0 as the parity drive? Specifically, the server will first be populated with 5x 4TB 5400 RPM data drives and 6x 3TB 5400 RPM data drives. I would like to use two 2TB 7200 RPM drives in RAID 0 as the parity drive to create a 4TB parity drive. RAID 0 for the parity drive would be setup with the hardware RAID controller and combine the two drives for 4TB. This should make the parity drive twice as fast as a single drive and I am wondering if anyone has tried this before? I realize that if either of the parity drives fails in RAID 0 that the parity data would be lost. But the parity drive could always be rebuilt if that happens. The tremendous speed increase for writing and parity checks would be fantastic though. I also do multiple writes simultaneously so faster parity would be very nice. Thoughts? craigr