sata300 how fast are they?

I am  looking in to putting together a new pc and I was looking a sata300 and I want to know if the hype on them is as good as they say. I have heard that rpm set the limit on data transfer speeds. Can anyone sed some light on this subject? Please
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RAID 5 is suited to lots of small writes - fast to do the calculations.  Overall it performs well and provides a fairly cost effective level of security.  For large files it does not do so well but in the end it is still good.

Here are some benchmark tests from Tom's using WD Raptor's in RAID 5 SATA arrays from 3 - 8 drives in size,
They are using a half decent controller for this test but it is actually not a true hardware RAID card.  It gives you a fair idea of what to expect.

The ASUS board also supports RAID 10,  which although expensive, provides good throughput AND high level of redundancy.  It is expensive since you need double the number of drives - so for the capacity of 2 disks you need to buy 4.  For raid 5 you could buy only 3 drives.  RAID 10 is fast because it does not do all the parity calculations of RAID 5 and it also gets speed for the same reasons RAID 0 is used.  For this reason it is also a lot less expensive to implement as compared to RAID 5,  so you see a lot of very inexpensive cards with RAID 10 or 1+0 or 0+1. (They are not all the same but are similar)

The other factor with a lot of the RAID cards for SATA is they do not provide real hardware RAID.  So in the example meyersd gives a lot of that work will actually be done by the system and not the RAID controller.  If you check add on RAID cards you will see that the good cards cost a lot and provide the onboard cache and processing.  Take a look at stuff from guys like 3ware ( ).

As with most anything top performance will cost more.  Cards from Promise do perform well and are really inexpensive and do just fine for many people.
Duncan MeyersCommented:
To put it into perspective - the sustained transfer rate for a Seagate Barracuda is quoted as >58MBytes/sec which is a best-of-all-worlds figure. That figure would have been attained doing a large sequential read operation. Realistic real-world figures for normal operations (that is; a mix of random and sequential reads and writes with lots if seeks in between) would be in the order of 20MB/sec and less.

So in answer to your question, the SATA transfer is largely irrelevant as the transfer rate onto and off the disc is much, much less.  You might be better off spending teh extra cash on a faster proc or more memory or a faster video card...

FWIW - In the product specs for their 15K SCSI drives Fujitsu give real-world performance figures for different applications ie booting, random reads/writes, highly random reads/writes, sequential etc etc etc. It pays to have a look at their PDF product brochures as they are quite eye-opening. Its nice to see a company quoting figures that you can actually expect to see in normal operations rather than the fictional maximum figures that look so good in brochures...
Here's some info that I did for another poster that brings up a comparison of SATA types,

The SATA II drives are better performers but once a drive like the 10k RPM Raptor's also get a new interface then we will start to see some really fast SATA drives.

I think the big thing to keep in mind is that the hype on the burst transfer rates or the 'potential' to transmit at high speeds is largely that - hype.  Sustained rates are better but not anywhere near double,  which is what it sounds like it is supposed to be.  But then the cost for SATA II is also not a huge jump either.

Right now there are not a lot of SATA II products but that will change soon.  So when and if somebody like Western Digital does release a Raptor with NCQ if you already have SATA II controllers you will be ready.
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gclessienAuthor Commented:
I like both your answers. raid 0 is the way to get the best speed out of the drives. I have one other ad-on question.  Do you thing that a raid 5 would be still be faster than a single drive.  I was look at the Asus A8N-SLI motherboard and using the raid 5 option.
Duncan MeyersCommented:
RAID 5 is faster than a single drive for reads, but slower (much slower) for writes. Here's why: for a read operation, the RAID controller can pull data off the multiple drives in the array almost simultaneously making it faster than using a single disc. However, every RAID 5 write operation involves 4 background disc operations: 1: read original parity, 2: read original data, XOR parity and data to get a partial parity, XOR partial parity with new data to get new parity,3: write new parity,4: write new data. That is why RAID controllers usually have cache memory - you write to the cache and let the RAID controller take care of writing out to disc in its own time. The problem here is that there must be some sort of backup (usually rechargeable batteries) for the cached data in case of powerloss/BSOD/etc.. It all costs $$$. In short, to get acceptable write performance from a RAID 5 array, you need write caching but to assure data integrity it must be protected.

RAID 0 is not RAID because it but nas no, none, zero, zip, nada, nyet redundancy. Lose one disc = lose your data. It is fast, though.
check out the graph at the bottom of this page for a graphical representation
As a real-world example, I set up two WD 74GB Raptors in a RAID-0 configuration with an MSI K8N Neo2 motherboard and ran HDTach3 on it.  I got 100MB/sec sustained throughput, so there is quite a lot of room before the SATA150 limit is hit.  For comparison, a Seagate 200GB IDE drive started at 80MB/sec and dropped off as it approached the center of the spindle.
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