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Re: Imported DB runs SLOWER on faster machine

From: Svend Jensen <svend.jensen_at_it.dk>
Date: Tue, 23 Jul 2002 16:25:55 +0200
Message-ID: <3D3D6773.4000206@it.dk>


Rick Denoire wrote:

> Hello
>
> I just exported some schemas from an Oracle DB (8.1.7, Solaris) and
> imported them into a Test DB (Windows NT). Die PC is somewhat faster
> than the Sun Enterprise 3500 (although it has 4 CPUs , UltraSparc II,
> and a Raid), as I could confirm doing some tests without the DB.
>
> But some long running applications seem to never end on this PC. A job
> running about 4 min on the Sun system seems to run for DAYS not! I was
> able to determine that it definitely has something to do with I/O.
> Well, this PC has a cheap Promise controller and a Raid 0 system with
> 4 EIDE disks. As I said, using other applications and benchmarks
> proved that the system is really fast (Athon 2000+ MHz, 1.5 GB RAM,
>

>>50 MB/sec sustained transfer rate from the harddisks.
>>

>
> Two possibilities:
> 1 - the data chunks read by Oracle mismatch the overall stripe size of
> the Raid 0 disks. Oracle always reads at least db_blocksize x
> db_file_multiblock_read_count. I could not find out the stripe
> parameters, because there was no chance to reboot the PC.
>
> 2 - Datafiles on the NT system are too large (>20GB). I just forgot
> that it is not Unix :-) Could anyone comment on maximum Oracle
> datafile size under Windows NT SP 6? But hey, the DB works somehow.
>
> Anyway, when the application runs, there is ALWAYS contention of type
> db_sequential_read, and as one updates the number of logical read
> blocks, it is possible to see how slow this operation works. The CPU
> is almost idle, contrary to the Raid.
>
> But I still know nothing about the real CAUSE of the problem. Could
> any one out there give me some hints about how to identify it?
>
> Thanks a lot
>
> Rick Denoire
>
>

I can hardly believe you think a PC with 2000Mhz cpu is faster than a 4 cpu UltraSparc II with raid !
I have a tractor with ~170 HP engine, and it can not outrun my small car with a 90 HP engine.
It takes more than clockcycles to perform and you have a long way to go. Wasted clock cycles are gone forever, among others....

/Svend Jensen Received on Tue Jul 23 2002 - 09:25:55 CDT

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