Re: Raw Devices: Increased Performance?

 I dont mean to sound too ignorant..but what exactly is a cooked and  raw database (?). We are talking about Logical volume manager databases  correct? The only one I have seen on svm is the one that is used also  with raw device vols (which are not newfsed, my understanding)and regular  filesystem type vols. These are usually placed in slice 11 (for us) as  partition type 6, which I assume is always raw ? no?

  -chris

ps: I have never hosed an svm database myself, I did get them out of synch, say

    if a pbay went down , and it didnt come on during bootup, but I always     have two good database which make for the error (usually placed on qcic 0)     which my understanding svm does an rdcp to replicate those db's, which     means that they are always raw? no?

Kurtis D. Rader (krader_at_crg8.sequent.com) wrote:
: This makes me think of the favorite TLA of the sales force:
 

: FUD: Fear, Uncertainty, and Doubt
 

: joelga_at_rossinc.com (Joel Garry) writes:
 

: >There was a thread on this a while ago, with some folks claiming minimal
: >increase, while others claimed up to 300%.
 

: >Personally, I think the one time that someone unthinkingly writes over
: >the raw system will more than make up for any increase. In other words,
: >it requires greater control over administration than any place can be
: >expected to have over a long period of time.
 

: This is true only for raw disk partitions. If you are using a
: logical volume manager (ala Veritas VxVm or ptx/SVM) then the risk
: of overwriting your raw database is no greater than overwriting a
: cooked database file. And in fact I have never taken a call from
: a customer who has accidentally destroyed his raw database. Yet
: I have taken four calls (that I can remember) in the past six years
: from customers who have accidentally blown away their cooked
: database. For that matter, I ran both raw and cooked databases
: back when I was a sysadmin/DBA and never had a problem with either.
 

: This is something I have studied extensively in my role designing
: system architectures for some of the largest Oracle sites in the
: world. Performance is actually pretty low on my list of reasons
: for favoring raw over cooked databases. A matrix I use when
: discussing this with clients shows the number of factors in favor
: of raw outweighing the number favoring cooked. That des not mean
: I always choose a raw implementation. It simply means that you
: shouldn't let FUD (see the start of the post) drive a decision.
: --
: Kurtis D. Rader, Senior Consultant krader_at_sequent.com (email)
: Sequent Computer Systems +1 503/578-3714 (voice) +65 223-5116 (fax)
: 80 Robinson Road, #18-03 Currently on assignment in the
: Singapore, 0106 Asia-Pacific region
Received on Sat Jun 29 1996 - 00:00:00 CEST