Energize said:
Cant you just use 2 controller cards? With raid 1 a lot of people never see any performance difference but it should give a big improvement to transfer rates, so something must be holding it back surely?
Raid 1 is not about performance, but about redundancy. You don't see any perfromance boost from RAID 1 since in essence you only have one drive. The second drive is essentially just a duplicate that mirrors all the movements of the primary drive, hence there's not going to be any effects on performance from it being there. (Very high end/expensive controllers might have enough smoke and mirrors to allow the mirror drive to not just be a clone but to do independant reading which would improve read-only performance, but very few controllers actually do this, and expect it not to be present on consumer level controllers...)
Raid 0 however is about performance since it keeps different parts (stripes) of a file on different disks. Thus, both for reading and writing, both disks deal with independent workloads and can thus contribute to throughput. But it increases the probability of data loss as you essentially lose the entire array if either of the disks break.
Motherboard controllers that sidestep/avoid the PCI bus can veritably scream in RAID0 setups. I've got 2 Raptors in RAID 0 on my Via onboard controller. They sustain slightly over 140Mb/sec for a sizeable portion of the disk, and never drop below 130Mb/sec or so anywhere on the disks. The same array on the other onboard Promise controller only manages about 110Mb as it has to work via the PCI bus. One Raptor can only do about 70-75Mb/sec so that clearly shows you that you get nearly double the transfer speed using my one onboard controller. FWIW, I have seen reports with people having 4 Raptors in RAID0 who sustain around 260Mb/sec. IIRC this was with the Intel ICH6 (or whatever) chipset.
IMO a RAID0 setup with a suitable backup regimen is quite satisfatory for most purposes, and in some ways required regardless of whether you have RAID1 or not. (The danger with a RAID 1 setup without other backup is that it provides no protection from software malfunction or user error. If a virus or some other malware for example deletes all your files, or if you accidentally do so yourself, then those operations would've happened on both drives simultaneously, robbing you of any recovery path you might've had. Similarly, if some other disaster happens, like your powersupply fries itself and shorts/overloads the hardware, then you very well might lose both your drives, again leaving you no recourse. By contrast, a scheduled backup every day or week or whatever onto a seperate backup drive, particularly if the backup drive is kept offline and/or seperate from the disks being backed up gives you a fallback route regardless of what calamity might befall your drives.)
