IDS Forum

RE: Cooked files vs Raw disc

Posted By: malcolm weallans
Date: Thursday, 9 December 2004, at 6:10 p.m.

In Response To: Cooked files vs Raw disc (Peter J Diaz de Leon )

This is a question I have answered many times in the past 17 years. And
the answer is always the same. If you use cooked files your performance
will be slower as informix cannot take advantage of the contiguous disk
access. And the 10 to 15% reduction in performance is assuming that you
create "clean" cooked files. If the cooked file is on a well-used file
system the performance overhead of cooked has been seen to be much more
than 10 to 15%.
But it isn't only that.
When I look at any IDS system I look at issues like cooked versus raw,
extent sizing, evidence of thought given to disk placement, no of logs,
log sizing, config parameters, etc. If it is evident that "quick"
answers have been used it is quite likely that the system hasn't been
thought about very much at all. And if the system engineering hasn't
been done then it is quite likely that the system is vulnerable to more
problems.
I am currently working with a number of systems that have not been
engineered and they all seem to suffer from similar problems.
Performance is very good - most of the time. And in one recent case the
customer has upgraded their processor power by about 20 times, with
faster disks, and more memory, and already within 3 weeks they are
seeing performance oddities. And nobody did the system engineering
because in testing it was like the proverbial "s**t off a shovel". I am
now considering a shutdown to correct some little things that were
overlooked.
So, the advice of one of the longest serving Informix DBAs is - do the
engineering. It might take longer but it's worht it in the long run.

Regards

Malcolm


-----Original Message-----
From: forum.subscriber@iiug.org [mailto:forum.subscriber@iiug.org] On
Behalf Of Peter J Dia....
Sent: 09 December 2004 19:28
To: ids@iiug.org
Subject: Cooked files vs Raw disc [3863]



I has a bit of a discussion with one of our developers today and the
topic of cooked vs raw file systems came up, and I am looking for
opinions.

Reason 1 for not using raw disc was that a 10% to 15% reduction in
performance can be made up in hardware
using a caching controller with lots of memory. Also the time involved
in setting up and maintaining raw partitions is to time consuming.

Reason 2 for not using raw disc was that if you use cooked files when
its time to move from the test environment to production
you can just TAR or ZIP up the cooked files and transfer them to
production and you are guaranteed that the tested TEST environment get
to production.


Thoughts?

Thanks




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Messages In This Thread

• Cooked files vs Raw disc
  Peter J Diaz de Leon -- Thursday, 9 December 2004, at 2:28 p.m.
  • RE: Cooked files vs Raw disc
    Gregory S. Williamson -- Thursday, 9 December 2004, at 3:10 p.m.
    • RE: Cooked files vs Raw disc
      Juan Manuel Naranjo -- Thursday, 9 December 2004, at 3:28 p.m.
  • RE: Cooked files vs Raw disc
    Michaelis, Daniel -- Thursday, 9 December 2004, at 3:47 p.m.
  • RE: Cooked files vs Raw disc
    malcolm weallans -- Thursday, 9 December 2004, at 6:10 p.m.
    • RE: Cooked files vs Raw disc
      Obnoxio The Chav -- Friday, 10 December 2004, at 3:17 a.m.

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