Re: Hardware/OS recommendations for large databases

At 01:18 AM 11/27/2005, Luke Lonergan wrote:
>For data warehousing its pretty well open and shut.  To use all cpus
>and io channels on each query you will need mpp.
>
>Has anyone done the math.on the original post?  5TB takes how long
>to scan once?  If you want to wait less than a couple of days just
>for a seq scan, you'd better be in the multi-gb per second range.
More than a bit of hyperbole there Luke.

Some common RW scenarios:
Dual 1GbE NICs => 200MBps => 5TB in 5x10^12/2x10^8= 25000secs=
~6hrs57mins.  Network stuff like re-transmits of dropped packets can
increase this, so network SLA's are critical.

Dual 10GbE NICs => ~1.6GBps (10GbE NICs can't yet do over ~800MBps
apiece) => 5x10^12/1.6x10^9=  3125secs= ~52mins.  SLA's are even
moire critical here.

If you are pushing 5TB around on a regular basis, you are not wasting
your time & money on commodity <= 300MBps RAID HW.  You'll be using
800MBps and 1600MBps high end stuff, which means you'll need ~1-2hrs
to sequentially scan 5TB on physical media.

Clever use of RAM can get a 5TB sequential scan down to ~17mins.

Yes, it's a lot of data.  But sequential scan times should be in the
mins or low single digit hours, not days.  Particularly if you use
RAM to maximum advantage.

Ron