SATA vs. SCSI..the debacle begins?

[sharpweb]

Who's tried out the new Serial ATA drives on a production machine?

Anyone roll out with a threeware RAID card doing RAID 1 or RAID 10?

How'd it do? Fly like an eagle or crash and burn?

-Sean

[JeremyV]

While I can't comment in a server environment, I have a home machine running Serial ATA drives running RAID 0 right now and it does fly. The best thing about SATA is the very small cables, thus leaving your case almost empty for optimum airflow.

But I would like to see some benchmarks comparing SATA vs. SCSI in various machines and RAID configurations.

[sharpweb]

Toms hardware had a nice benchmark of some of the earlier stuff put out by Western Digital...but that drive is too small to be any use.

How long have you been running them? Have there been any issues? Have you tried running them with linux and if so what kind of controller did you get?

-Sean

[JeremyV]

Right now I'm running dual Seagate SATA Barracuda 80GB drives. They are using an onboard Promise SATA/RAID controller. At first there were a few performance issues do to something in the stock motherboard BIOS version. But that has since been resolved and SATA performance has increased about 400%. Otherwise WindowsXP didn't have a problem at all recgonizing the array.

I have yet to try Linux in this system, I have just built it a week or two ago and am still playing with it :D But soon here I am going to be repartitioning the arrary and re-installing both XP and most likely Mandrake or Redhat. I run those both on my laptops, but would like to test out some things on linux as well.

One thing I will say I dislike about SATA, is the way the power and data cable connect to the drive itself. While it is small and uses very few pins, it reminds me of some cell phone connectors, which are kind of flimsy and can break really easily. I would have liked to seen some sort of locking clip or more sturdy connector, but if you're careful you won't have a problem.

A pic of the connectors... notice the gold contacts, they are on the bottom of a really thin piece of plastic:
http://www.ocworkbench.com/2002/seagate/sata/Picture%20067%20copy.jpg

[sharpweb]

Let me know if anything breaks when you install linux :-).

What raid level are you running at?

-Sean

[JeremyV]

I'm running RAID 0 right now, since this machine is used for high-end graphics and the occasional game.. I wanted raw performance as my backups are on seperate drives anyway. I do need to test out various RAID types and make sure each runs properly though.

But just some numbers from my drives right now... I can say, it IS fast, and at literally a fraction of the cost of SCSI, I think it has a lot of potential.

Buffered Read: 876 MB/s
Buffered Write: 1.2 GB/s
Sequential Read: 68 MB/s
Sequential Write: 81 MB/s
Avg. Access time: 7 ms
Random Read: 8 MB/s
Random Write: 13 MB/s

When compared to a SCSI U160 (15krpm, 8MB cache) drive, the SATA RAID beats it's performance by almost 30%. And two SATA 80 GB drives only cost me about 300 dollars total. How much would two 80 GB SCSI drives cost you? ;)

Really looking forward to the second generation SATA drives coming out in about 2 years, they double the performance specs we have right now.. and in 2007, the 3rd generation even doubles that again, which will be just insane... but I still think hard disks are going to be the bottleneck. Their technology just can't keep up with the ever increasing ram/CPU/video technology. Not until we move to solid-state drives...

[sharpweb]

drools all over solid state.

[tpetersen]

Originally posted by JeremyV:

When compared to a SCSI U160 (15krpm, 8MB cache) drive, the SATA RAID beats it's performance by almost 30%. And two SATA 80 GB drives only cost me about 300 dollars total. How much would two 80 GB SCSI drives cost you? ;)




Of the reviews I have read it looks like SATA is promising but still has a ways to go to get to the performance level of SCSI. One thing you have to consider is that SATA still uses the CPU's process for operations whereas SCSI offloads this to a dedicated controller.

Another thing to consider is the reliability of SATA. A typical Seagate SCSI drive has something like 1,200,000 hours MTBF. I have seen many non SCSI drives with less than 1/4 of those hours.

I will conceed for the non server / business market SATA is going to be a cheap and fast alternative to SCSI. At this time I don't see SATA taking any business away from SCSI in the higher end workstation or server market.


TP

[sharpweb]

I'm going to throw stuff out every 2-3 years anyway. MTBF shouldn't be an issue even if its only 300,000 hours.

What operations do SATA offload to the CPU? I'm not familiar with them. Please educate and inform! (I have been looking at the threeware RAID cards and I thought that they provided a pure hardware IDE RAID solution.)

For high-end stuff I don't think that SCSI will be displaced yet, although the size vs. price point of SATA is VERY attractive.

-Sean

[JeremyV]

You could always get a seperate SATA controller card if you are concerned about CPU load, but when I ran my benchmarks, even with an onboard raid controller, CPU utilization very low for an onboard device, less than 6% when under full load.

I don't have a SCSI system here to compare it to, but I think the difference would be marginal if both were using addon controller cards.

The only thing I'm not completely sure on is data integrity. I know SATA now impliments CRC checks when standard ATA did not. Does SCSI do this, or have it's own error correctoin methods? I'm not as well versed in SCSI hardware.

[sharpweb]

I believe SCSI does have its own error correction. Darned if I know what its called. I was looking at 3ware and ah someone came out with it...Escalade(ug what a name.)

I've had luck with the rocket raid stuff in the past also.

-Sean

[no1v2]

SATA isn't supposed to compete with high-end SCSI, it's basically initially being targeted as a replace for low-end SCSI, since it's basically dead. I do think it will eventually completely replace PATA though. PATA is already considerably more cost effective than SCSI, there are just times when you need SCSI. 10,000(+) RPM SATA drives reduce the number of those times.

3ware is almost always the way to go for IDE RAID. Don't even bother with "quasi-hardware" RAID cards (like the Promise FastTrak and HighPoint RocketRAID, and Adaptec 1200A series). Promise does make a true hardware IDE RAID controller (the SuperTrak), but it's big, expensive, and slow. Adaptec's true hardware card (the 2400A, 4 channels) is good too, but bigger and more expensive than 3ware's 4 channel one. For the most part they perform about the same, with the Adaptec doing better in some tests and the 3ware in others. The adaptec does have expandable memory though (comes with 32MB), which could give it an edge over the 3ware if you're willing to sport for it. Always get fast RAM for a RAID controller. The Adaptec for example performs better with 64MB of CAS2 than 128MB of CAS3!

Btw, I think 3ware was using "Escalade" before Cadillac ;)