Re: 1 Volume Raid 10 vs. n Volumes Raid 1

> > how do I get more I/O performance with Oracle, with one large volume
Raid
> 10
> > or better with several smaller Volumes (1 volume per disk) Raid 1?
> >
> > We have 2x 7 drives with 18 GB each, the size of the Oracle tables and
> > indexes varies between 10 and 4000 MB.
> >
> > With the first possibility, one large volume Raid 10 I assume:
> >
> > pro: read and write performance for one single data object should be
best
> > because of distribution over all disks
> > con: when reading/writing several tables, or tables and indexes at the
> same
> > time (multi-user), performance might be bad when the same disk is
involved
> > several times
> >
> > With the second possibility I can control where each object is located,
> > especially separate tables and indexes or partitions.

> The performance will be better with the Raid 1 configuration. The
advantage
> is in getting your objects separated onto different physical disk drives.
A
> characteristic of any raid that includes striping, (commonly 0, 3, 5 and
6)
> is this, it is very efficient for reading or writing large blocks of data
> because it aggregates the I/O of all of the drives, however it is very
> inefficient for reading or writing small blocks of data because of the
> increase in average seek time. Oracle works with small blocks over many
> files (datafiles for data, indexes, temp, roll back, and often audit logs
> and others, plus redo and archive logs. Raid 1 will be a bit slower than
> discrete drives but faster than 0+1 for an Oracle DB.

I partly aggree but want to add something. When using n RAID 1 volumes you have to take care that you don't put all the datafiles of the most used tablespace on one disk (manual striping). Personally I'd prefer RAID 10, with an additional (RAID 1) volume for redo log files.

Regards,

Knut Received on Tue Aug 13 2002 - 04:10:08 CDT