Re: datafiles size limit

Nabil Courdy wrote:

> We're getting ready to install a document management
> system running on Solaris and Oracle 7.3. The vendor
> is recommending to setup the tablespace as follows:
>
> One 120GB tablespace consisting of 6 raw
> datafiles, 20GB each.
>
> My concerns are:
>
> 1) Can one datafile be larger than 2GB in 7.3 on Solaris (2.5)
>
> 2) Does Solaris support logical volumes or something
> similar which can enable me to create large filesystems

Check the docs., Sun web site? Sorry, I'm more AIX. I'm sure a Sun expert will step in.

>
>
> 3) My preference would be NOT to use RAW devices.

Why, lot less hassle than filesystems when setting up a system of this size. Get yourself a decent backup tool that runs with EBU and you never have to worry about 'dd'.

>
>
> 4) Outside of the possible 15% performance improvement that
> RAW devices can yield, is there any other good reason to
> have RAW files as far as disk space management and
> supporting large tablespaces go?
> tablespaces fo?

This will start another jfs v raw debate that will go on for weeks! :-) My advice is to do some testing and get some feedback from other customers with similar systems. I like raw, under AIX's LVM they cut out half the work over setting up and maintaining jfs (you can't create a jfs until you have a raw partiton anyway, but Oracle only needs the raw partition, so why create the jfs?..)

You might see slightly improved read performance with jfs, but this will soon evaporate when you have multiple active users all jumping at the filesystem buffer caches, and with raw that freed up cache memory can be put to much better use as Oracle SGA, sort areas, etc, so raw isn't such a bad choice for databases. From my testing, I've found raw to give better performance overall, but never really as much as a solid 15% across the range. I'd say 5-10% is more likely. Test you own system and find out for sure.

As regards 20G partitions, that seems way big to me. That's a lot to restore if you have to pull a datafile (or partition) back off tape). I'd suggest a smaller 1-4G range as more suitable. Still, if these are set-up as stripe sets across unprotected drives you'll have to pull back the whole stripe set anyway... Be careful.

Regards,

Steve Phelan

(Oracle 7 & 8 OCP)

>
>
> Nabil Courdy
> mooab_at_emirates.net.ae (Sub moab for mooab)
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>
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Received on Mon Feb 22 1999 - 16:53:20 CST