Can I do this and how? 2x raid 0

[guido06]

Hey there,

I am new to raid, but have been doing some research on it. I have an ami Megaraid ide 100 card and I would like to to the following with it: install 4 x 40 gig IBM 7200s, but I want to have 2 on one array to be recognized as drive c: and 2 on another separate array as drive d:. Anyone ever done this? I have been told I would have to set it up in the following way: master+master = c: and slave+slave = d: or 1+3=c: and 2+4 =d: I know that if I only run two drives and stripe them in 0 the performance is worse than just having two drives on separate channels non-raid, (when writing directly from one drive to another). So, in theory if I can have 2 separate raid 0 arrays (4 drives total) my transfer rates should be close to double that of 2 non-raid drives. Any help and input would be greatly appreciated.

[chemmajik]

Everyone I see suggests having raid drives on there own cables, never sharing. If I had 4 40g drives I'd make 2 raid 1 drives just to be on the safe side. But if you are going to just use them for just holding data, and not doing alot of rewriting(except mpeg2) you may not have any problems. You might want to have a seperate boot partition on the onboard ide that keeps the important stuff. I think I have seen some people doing what you are wanting to do, but they are using a seperate SCSI raid for there boot drive or just using scsi, seperate from the IDE raids. Sounds like fun...

[xzquala]

you should always put your operating system on a non raided disk.

I know many people that have had a horrible time getting their system to boot properly when the os is on the raid card. I have not had much experience with raid lately, so I don't know if it has improved much here or not.

The problem I have seen lately with raid cards I could afford is that they say they support 4 drives, but they only have two ide connectors on them. this flavor of raid does not allow for striping 4 drives, you can only stripe 2 drives at a time. that gives me no reason to raid. the advantage of striping two drives is not significant enough, and in some tests, there is a decrease in performance.

one thing I would like to do is build a new system with 5 drives in it. one drive just going off of the plain old ide bus. put the os here, boot from here. the other four drives raid striped and set system enviroment variables to put the profiles (my documents and such) and the program files folders on the raided drive.

does anyone know if there is a consumer-level raid card capable of this? if so, I just might have to get back into raiding.

[FranchiseJuan]

Many people have said that raid setups have worse performance then indivigial drives, but I find this to be wrong. My raid setup (two IBM 40g on hipoint 372, raid 0) has much better performance then when it use to be just two drives. The drive index in Sisoft sandra use to not indicate this, but this was before I found out that VIA chipsets have a problem with raid. You need to install a patch to get it to work properly.

Can't remember where I got this patch... Do a search it should not be hard to find.

Even if you could setup two striping sets on two channels, would you really want to do this? The performance would be not nearly as good as having drives on seperate channels. If you want to get Four drive IDE raid 0 striping, then you should probably look at getting a four channel IDE raid card or motherboard (Abit AT7 anyone?).

[theReal]

I have not had much experience with raid lately, so I don't know if it has improved much here or not.

I think it has, I have two examples: first is my dad's system (which I set up to be capable of DV editing, so it's basically my second workstation - he wouldn't need such a good computer...).
He's got two Maxtor DiamondMax 30GB hd's (5400rpm) which are unfortunately the worst drives for IDE Raid (has something to do with their caching strategy I think, a lot of people reported these drives to be very bad for RAID setups). The controller is a Fasttrak UDMA66 RAID, which was one of the first IDE RAID controllers available. Then, he also has an Epox 8KTA+ board (VIA KT133). Something is definitely not working there: as RAID0 (striping), the drives perform much worse than as single drives, plus the transfer rate curve in HD tach is very weird jumping up and down with a lot of spikes. Eventually (even more often when the VIA patch is installed!) the drives will completely stop transferring for up to 10-15 seconds, halt the whole system in the meantime, then go on like nothing had happened. This happens only on file read, not write.
I finally installed them as a span-raid, which made them perform better (like normal single drives), but the sudden halts were not completely gone. Raising the PCI latency to 128 completely solved the problem. Most probably there are problems in all components: adapter and chipset, and harddrives.

Second (positive) example: My own system. Two WD 60GB (5400rpm) drives as RAID0 on the onboard HPT UDMA100 controller of my Epox 8K7A+ (AMD 761 chipset). Since I installed the drives as RAID, I haven't had a single problem, the transfer rate reported by HD tach went up by a few mb/s, the Sisoft Sandra Test went from 24000 to 38000 points, the access time actually feels much better, also large file-copy operations seem quite a bit quicker than before.
Only positive results, nothing negative about it, even I boot Win2k from the RAID drives.

So, I'd say controllers as well as harddrives must have become much better apt for use in a RAID0 system.

[The Belgain]

Why would you not want to have the OS on the striped RAID drive? Surely putting the OS on this drive would vastly increase system performance?

[theReal]

I don't know - my system boots just fine from the RAID. If Windows wasn't on the RAID, I could have used software RAID in Win2k. The only reason I wanted a "hardware" RAID was because I wanted windows to be on it.

I backup my data more often than before, though. When the system badly crashes, you can't just put the RAID in another computer and read the drives. I've seen a friend losing 40GB of mp3 that way (about 35GB weren't backed up at all). OK, in his case it was a win2k software RAID and he did a fresh install without thinking about it. Then he couldn't recover the data, kept the drives unchanged for quite a while and tried everything (even more than everything), but the mp3s were lost...