help !!!
please ):

SAS Raid 6, would be the way to go.

SAS is mich faster then raptors, but also cost more and generate more heat and noise.
If you dont mind that and need fast performance i would go for SAS.
I am using 2 SAS 15k rpm 138GB hdd in raid 0 and it can go up to 492 MB/s peek and 236MB/s average reading speed (unfortunately on vista is somehow weirdly limiting speed to my Adaptec SAS adapter cache capacity 128MB/s regardless if use single drive or any other raid config, its till same, 126MB/s ).

Its been a while since I've delved into more than your basic RAID 1 or 0 so bear with me if I make any mistakes.

First off, the issue here isn't SATA vs SAS, its 10k vs 15k RPM.

To get RAID 5 you need at least 3 drives and for RAID 6 you'll need at least 4. RAID 6 provides an extra level of fault tolerance but tends to be slower than RAID 5 because of the extra set of parity that needs to be calculated and written. For overall size RAID 5 is number of drives (N) minus 1 -> N-1. For RAID 6 the overall capacity is N-2. These are both due to the parity data contained on the drives. For the best performance with some fault tolerance I'd recommend a RAID 5. You might also consider a RAID 10 although you'll wind up with less usable space. With RAID 10 you need at least 4 drives and you must use an even number. Also the amount of usable space is N/2. Quite frankly I forget which is faster RAID 5 or 10 at a low number of disks and I also don't remember how well they scale. It also depends on how capable of a RAID controller is being used.

Hope that wasn't too convoluted and that it helped somewhat.

-mcg

Concerning sound,heat and the work that involved, i go with 10k.

Anyways all those records will be in database and your WS involves in lot of reads and writes.

10'k's and little extra RAM is good,15k SAS i found pretty noisy.

No RAID, one for OS and the other for apps, backup scheduled daily.

Not necessarily. The new SATA2 drives running in AHCI with disk write cahching enabled are great for Server configurations. Alot of the Dell Power edges that I have been installing in the Banks in Canada are now using the newer SATA drives instead of SCSI.

PS to the OP, if you want future proof your build I may also go with the SATA drives since it seems more and more that SCSI is becoming obsolete. (Note: phasing out is more like it)

However I agree 100% with using Acronis... great utility and fairly easy to configure and use.

I love both my raptors in Raid 0, but If I had the money I would go for the SAS for sure!

OK if all you are going to get is 2 drives get the SAS 15K drives,
Use one for OS and Apps, and the other for data.
And back up you data every day to DVD and an external drive.
If you can get XP Pro, Vista still has some I/O overhead issues.

I'll give one suggestion. Since you primarily work with business apps, you might consider XP 64 bit Pro. I've used that on my business computers and found it better (faster) at handling large files than 32 bit XP Pro. Since Vista came out, all problems with drivers have disappeared, which were few in any case. Just something to think about.

supremelaw,

1. Whether the data fits into the HD's cache is not the only issue. It's how the application treats the storage system.

For databases, it doesn't matter if the transaction fits inside the HD's cache or not, because the database's storage driver will wait until change log is actually updated, and then wait until the change is committed to the database file before proceeding. Due to the transactional nature of the application, it doesn't really matter if you have a gigantic cache, the database won't use it because it has to treat certain writes as atomic.

A file server has some of the same issues when updating the NTFS file journal and MFT.

2. RAID cards' cache has a lot more functionality than just holding the pending write. For RAID 5, the on-board cache of the RAID controller is vitally important to increase performance because of write combining. Holding pending writes in cache and waiting for other writes that can be combined into a whole-stripe write can increase performance of RAID 5 writes by huge amounts. But this is irrelevant in this thread because the original poster is not going to implement any form of RAID.

3. There is no doubt that SAS drives, alone, in RAID, or in the Quadrapack would be faster choices than the single Raptors. However, the original poster was recommended SAS drives at the beginning of the thread but then chose against them, probably due to cost. So be it. His choice is Raptors, and you recommended to him an even slower solution. The fact that your Quadrapack setup is faster than the Raptors is true and also immaterial since that's not one of the choices the original poster has.

4. You're continuing to cite sequential transfer rate, RAID setups, and solid state drives, which is really an academic discussion. The original poster wanted practical recommendations for his specific situation, not a theoretical dissertation.

If you are on a budget I would get the Raptor, but seeing you are on a larger scale and will be using for business use primarily, the SAS drive will offer much more performance. I would definitely put it in RAID because those drives spin so fast that they can burn out kind of easily, and since your dealing with masses of records, you cannot afford to loose them.