RE: BINARIES - San or Local Storage
- From: Paul Drake <discgolfdba@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Thu, 26 Aug 2004 20:07:10 -0700 (PDT)
--- "Gogala, Mladen" <Mladen.Gogala@xxxxxxxx> wrote:
> Binaries on the local disk aren't faster then
> binaries on
> Symmetrix, as long as Symmetrix isn't configured as
> RAID-5,
> please pardon my French. If Symmetrix is configured
> as RAID-1+0,
> then it equals or exceeds internal disks in speed
> and clearly
> surpasses them in reliability. Problem is that you
> are not supposed
> to waste those internal disks either, so you should
> put there something
> that can be easily re-created. Oracle executables
> are (hopefully) not
> changing on the daily basis. If they are, then you
> have problem with
> gremlins who mastered software engineering, which is
> an especially nasty
> variety. Internal disks are usually connected to the
> rest of the system
> by 320 UW SCSI III with 320 MBit sec transfer rate
Mladen,
Its MegaByte. big M, big B.
I'm sure that you know this - but - I expect better of
you.
FibreChannel Host Bus Adapters are measured in
Gigabits per second (2 Gbps).
Ethernet adapters are measured in Megabit (100 Mbps)
and Gigabit (1 Gbps).
Good old SCSI (RAID or otherwise) has always been in
MB, way back in the days of wide SCSI (20 MB/sec),
UltraWide SCSI (40 MB/sec), Ultra2Wide SCSI (80
MB/sec), Ultra 160/m | Ultra3Wide SCSI ... and the
flavor you mentioned above.
320 MB/sec is the channel rating speed, nowhere near
close to the actual sustained transfer rate.
But an 8 drive RAID 10 array could give it a run ...
This might seem to be trivial, but it wasn't that long
ago that a landing craft crashed on the surface of
Mars ...
> while Symmetrix is
> usually connected by something called FC/AL (Fiber
> Channel/Arbitrated Loop).
> Fiber Channel in its latest incarnation surpasses
> 1GBit/sec, which means
> that FC controller is significantly faster then
> SCSI. Disks are usually
> produced by 3rd party vendor in both cases, so it
> doesn't really matter.
> You get 10milisec average access time,
no way. you cannot be serious.
average access times are much less than that for
decent server-class drives, unless your sysadmin gave
you those 3 x 146 GB drives in an ever so convenient
RAID 5 array.
> which usually
> turns into 30 milisec
> per I/O request, which is excruciatingly slow.
7 year old hardware, perhaps?
> Now enters the best EMC
> cash cow: cache memory.
SCSI RAID controllers have that also.
> It helps significantly
> reduce average disk access
> time, but it is not free. As a matter of fact, it is
> very expensive.
> Now is the time to stop the story, because we came
> to the point where I
> should discuss things like buffer cache efficiency
> and implementation,
> priority paging (implemented only by Solaris, of all
> unixes) and things
> from the Adrian Cockroft's "Ferrari" book, which
> definitely outside the
> scope of this list.
I would hope not.
> Mladen Gogala
If the FibreChannel Host Bus Adapter is saturated
performing as many IOPS as it can, then its likely
that you'll have better performance on the internal
SCSI RAID drives that also have a cache on the ROMB or
add-in PCI-X controller.
Anjo Kolk spoke about this at Hotsos.
Think Rambus RAM vs. DDR RAM.
Think current memory differences of Intel vs. AMD.
Often times, latency effects dominate as opposed to
bulk, nominal throughput.
For sheer throughput, you can't beat a cargo ship.
The 3 month latency might be a show stopper.
I think that we need to cover this over a burger and a
beer, sometime when you can take a 90 minute lunch
again.
Paul
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