p5w dh: best raid performance: ASUS EZ-Backup or Intel ICH7R
Anyone have experience using the ASUS EZ-Backup and Intel ICH7R RAID solutions for this mobo? I would like to know what option provides the best performance and stability with RAID 0
The best way to connect on this MB is through the ICH7R south bridge using the SATA1, SATA3 and SATA4 connectors. These connectors are directly connected to the south bridge. The EZ-RAID connectors are both connected to the missing SATA2 also via the ICH7R. Since the EZ-RAID uses a sharred connection, you only have half the bandwidth potentially for the disks connected in this way.
I have seen at least one person who claims 330 MB/sec = 3.3 Gb/sec burst transfer rates in RAID 0 using direct connection to the ICH7R. This same person said they only got 191 MB/sec using the EZ-RAID connectors. If you look at what folks on the Xtreme Systems forums claim, don't use the EZ-RAID if you want performance maximized. They have a lot more data over there.
The EZ-RAID setup adds a level of hardware between drives and the ICH7R that can further hurt performance. This seems to be confirmed by the results given above. The EZ-RAID does provide a number of nice services to maintain the RAID set in hardware (like data integrity monitoring) that will have to be done in software on the direct connected ICH7R ports (SATA1, etc.) So you loose a few CPU cycles using software but that is probably not as noticable as slower data transfer rates for very large files. Make sure you load Intel Matrix Storage Manager software in Windows to perform the data integrity monitoring. You won't miss the CPU cycles expecially if you are running a core-2-duo processor.
Quote:said they only got 191 MB/sec using the EZ-RAID
I'm browsing around looking for info to help me work out the same thing as the op and was wondering just how relevant this 3G/sec limitation is for the ezraid setup.
For large files surely the limiting factor will be the sustained data transfer rate from the HD's eg say a seagate 7200.10 supposedly can sustain a max of 78MB/sec so two of them in tandem could theoretically be delivering 156MB/sec absolute max.
That means it's using around half the available bandwidth upstream from the raid controller.
Even if it's delivering data from cache which can presumably deliver data much faster than 3G/sec it only gets a 32MB head start before it empties the cache and needs to wait on physical disk access. So any single read second that takes more than a tenth of a second has a max transfer rate of 156MB/sec anyway.
So what am I missing here?
(noob alert: I'm trying to understand this not trying to expouse anything) .
I don't think you are missing anything. The ICH7R south bridge feeds the Silicon Image Sil4723 chip which performs all functions in hardware to deliver the data to both hard disks plus some nice maintenance and error correction as well. Since the Sil4723 gets the full benefit of a full bandwidth connection (3Gb/sec) to feed it, the Sil chip should be able to feed both attached hard drives (EZ-RAID) without compromising performance. Now, having said that, the Sil chip does add another layer that must be traversed to get to the disk drives but I hardly think that would make a noticable difference given the max sustanined data rates of hard disk drives.
The very valid point you state is the max sustained speed of disk drives on the market today means that there should be no problem. Drives can't even meet SATA 1 speed limits much less SATA 2 in actual use. I have seen some claimed cases, like the one I repeated above, that show differences in burst rates but these are not sustained rates as you correctly pointed out. The later is what one MIGHT be able to detect in actual use if you are dealing with huge file sizes all the time.
In my own system, I have a SATA 1 RAID 1 data set. I used SATA 1 drives because I had installed them only 6 months previously on my old system which only supported SATA 1 spec. When I went to build new system I looked at a lot of data and claims and decided I didn't need SATA 2 spec drives because I would never see any difference in performance. The new Raptor drive I bought for the opsys can only be gotten in SATA 1 spec.
My new system is lightning fast and I am very pleased with my decision. I think SATA 2 is a marketing gimic because the hardware in real use can't perform to the level the electronics are capable of performing. The main benefit of SATA, IMHO, is the cost and size, safety monitoring, and data write optimization available versus traditional IDE disk drives.