Re: Please recommend a disk configuration for the server

What's wrong with 9GB drives? we don't know his situation, he might need 9GB drives because his APPLICATION_DATA Tablespace might/will be 6GB. I am not a NT system Admin, so I cannot comment on NT's mirroring.

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In article <3617EF5D.F2E30C45_at_nospam.usask.ca>,   Chris Pitzel <chris.pitzel_at_nospam.usask.ca> wrote:
> > The server has two FAST+WIDE SCSI adaptec controllers (bus
> > mastering). Controller #1 has two 9GB disks attached to it.
>
> The Adaptec controllers themselves are good and probably do not need to
> be replaced (in other words, don't rush out and buy a 2940UW just
> because you think you're going to get better performance -- you won't).
>
> > Disk 1 is logically partitioned into drive C+D, disk 2 is
> > drive E. Controller #2 also has two 9GB disks attached to it
> > which are mirrors of drive C,D & E. The mirroring is taken care
> > of by Windows NT. There is also a CD-ROM driver attached to
> > controller #1 but the CD is rarely used---only when installing.
>
> Mirroring done by NT is a bad idea. Stuff like that ought to be done in
> hardware.
>
> > 1. Add two more controllers to the system (we will end up with total
> > of four controllers then---we don't even know if it's possible) and
> > move two main drives to controller 1&2 and the mirroring disks to
> > controller 3&4. This way each disk has it's own controller and,
> > hopefully, the peformance will go up.
>
> The bandwidth to each disk is not the issue here; each drive probably
> only puts out no more than 5-7mb/sec at the best of times, 3-4mb/sec on
> average, and maybe even less with the database you are running.
>
> Even a fast wide PCI controller is adequate bandwidth wise, and there is
> no need to be adding additional controllers.
>
> 9 gigabyte drives really are too large for a database system though if
> it is heavily used; I would suggest that you not buy drives which are so
> large in the future, and use more drives to achieve the same capacity.
>
> > 2. Leave the current controllers and add a RAID controller to the
> > server. Move existing drives to the new RAID controller. Say good
> > bye to mirroring and let RAID worry about parallelism and distribution
> > of files accross different drives.
>
> A RAID controlelr is your best option; you really shouldn't be getting
> the OS (NT) to be doing what should be a function of the hardware
> (mirroring). That just imposes additional load on the system.
>
> My hunch is that 9 gig drives might be too large for your specific
> configuration as well. However, without knowing specifics about the
> loading/size/usage patterns of your database, I really can't comment
> further. All I know is that I would never configure an moderately to
> heavily used oracle machine with 9 gig drives.
>
> > The question: which of the above will yield in maximum performance
> > gain? The cost is an issue as well. If one solution only has about
> > 10-15% advantage on the other, we will rather go with the cheaper
> > one. As it stands right now, #1 (adding two more controllers) is
> > about one third the cost of #2 (RAID).
>
> You are going to need RAID one of these days; by procastinating now, you
> are just looking for more problems in the future. RAID controllers,
> properly configured, have a dramatic effect on the performance. Adding
> additional non-RAID SCSI controllers is an almost useless move since
> your present controllers aren't even being used to anything near their
> full capacity.
>
> You might also want to look into replacing those 9 gig drives with pairs
> of 4.5gig drives as well, in addition to the RAID controller. This does
> come at a significant expense though (why 9 gig drives were used in the
> first place in a performance-sensitive application is a mystery to me
> though).
>

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