Re: RAID 5 or 5 hard disks?

I agree that that is what happens, and that it is wrong. however I'd be interested to know exactly what sort of performance hit one gets from a machine with data & indexes on raid 5, but with well tuned memory structures etc.

regards

--
Niall Litchfield
Oracle DBA
Audit Commission UK
"Barbara Kennedy" <barbken_at_teleport.com> wrote in message
news:aW6Y5.3559$4W.419693_at_nntp1.onemain.com...


> My experience has been that Raid 5 gives you a large performance hit.  It

> may be true that if you have enough disks for raid 5 then it is okay.  But

> people who tend to use raid 5 (not all) are looking at the bottom line in

> terms of raw cost and not in terms of the cost of poor performance.  Thus

> they tend to buy the minimum (e.g. 3 disks) and not more (like 10).

> Jim

>

> "Niall Litchfield" <n-litchfield_at_audit-commission.gov.uk> wrote in message

> news:90qba0$3n$1_at_soap.pipex.net...

> > Hi

> >

> > Raid 5 is fine (so long as you have sufficient disks). However redo and

> > archive logs should always be mirrored. This suggests that you should

 have


> > as well as the raid 5 volume at least one mirrored pair for logs and

> > preferably at least 2. You can then put the os on one mirrored pair the

 logs


> > on another and the data on your raid5 set.

> >

> > You will always get better performance from striped and mirrored disks

 but


> > this tends to be expensive compared to raid5.

> >

> >

> > --

> > Niall Litchfield

> > Oracle DBA

> > Audit Commission UK

> > "Allen" <allenh_at_starbase.neosoft.com> wrote in message

> >

 news:BD71F762829CE2EA.D22E5AC688FEA19C.C4951E8FAF1A6749_at_lp.airnews.net...


> > >

> > > I've always installed my databases with indexes on one HD, RBS on

 another,


> > > etc..  now I'm in a new environment where they want to use a Raid 5

 disk


> > > box that will have all my datafiles in the same volume. Supposedly the

> > > RAID stuff will take care of spreading out the files on different HDs.

> > > Is this cool, or should I still insist on several different HDs within

 the


> > > Raid 5 environment?

> > >

> > > thx.. Allen

> >

> >

>

>