Re: Competition for OraPerf

HansF wrote:
> On Sun, 05 Nov 2006 22:02:17 +0000, Mladen Gogala wrote:
>
> > Actually, with falling prices of flash memory, SSD devices are becoming
> > extremely affordable, while CBO has become more complex and harder to know.
> > Fast disk devices are definitely a good option which is, in many cases,
> > cheaper then a top-notch consultant or a DBA needed to tune an application
> > system.
>
> I absolutely agree that SSDs are an option. Iit's definitely worth keeping
> as a possibility in the toolkit.
>
> Not sure I'd be willing to stake the performance and availability of my
> system on a removeable device on an externally shared bus. Especially one
> that tends to be restricted to FAT.
>
> But it's worth investigating. Especially if it speeds up the redo enough
> to delay using the async option of the commit statement.
>
>
> The thing that worries me is simple: is it a problem resolution? or is it
> sweeping a problem under the rug, to fix later?
>
>
> --
> Hans Forbrich (mailto: Fuzzy.GreyBeard_at_gmail.com)
> *** Feel free to correct me when I'm wrong!
> *** Top posting [replies] guarantees I won't respond.

Is flash (drive) memory synonymous with SSD? Flash drive memory, riding in a USB2 slot is not fast, especially when compared with a RAID controller with 256MB or more cache memory that is connected to a PCI Express bus. Compare the burst and throughput of a 6, 8, 10, 12, or more drive RAID 10 array with the performance of one of these 8GB flash drive:
http://www.pcmall.com/pcmall/shop/detail~dpno~7036586.asp

>From that website:

"Speed: Read 8M bit/sec, Write 6.4M bit/sec (Max)" Read speed on this 8MB flah drive is 1MB per second maximum, and write speed is 0.8MB per second maximum. Flash drives are also prone to corruption.

I am hoping that flash drives and SSD are not one in the same. My bet is that SSD plugs into an internal PCI slot and is essentially battery backed RAM. While fast, it would still be constrained to the maximum speed of the PCI bus, which is likely shared with several other devices, possibly the hard drive RAID controller. If this is the case, the addition of the SSD device could slow the maximum throughput of the hard drive RAID controller as it must now compete on the PCI bus with the SSD. This of course leads to the question, could adding an SSD device slow performance? Some servers with PCI buses actually have two independent PCI buses, so maybe this is not a concern.

Charles Hooper
PC Support Specialist
K&M Machine-Fabricating, Inc. Received on Sun Nov 05 2006 - 20:45:53 CST