IDS Forum

Re: Raw Partition Vs Cooked FileSystem

Posted By: Art Kagel
Date: Thursday, 11 September 2008, at 3:36 p.m.

In Response To: Re: Raw Partition Vs Cooked FileSystem (Jim Tranny)

But the block device is COOKED not RAW, it still funnels data through the
system buffer cache unless you use O_DIRECT mode IO. The Administrator's
Reference manual says:

DIRECT_IO is not used for temporary dbspaces and can only be used for
dbspace chunks whose file systems support direct I/O for the page size.

I have not tested whether direct io is actually used if you point a chunk to
a block device. Without direct IO block devices suffer a performance
penalty of about 10% which is nearly double the typical performance of a
filesystem file with direct IO enabled.

For maximum throughput, you still want to do the RAW binding if it's
available. The only remaining question is whether the possible 5%
incremental performance gain is worth the hassle of creating the RAW device
links/bindings and that's up to the SA's and DBA's on the scene. If you are
not pushing your system's IO capacity anyway, will you notice the
difference? Maybe maybe not.

Art

On Thu, Sep 11, 2008 at 2:24 PM, Jim Tranny <jimtranny@gmail.com> wrote:

> One ponit of clarification for Linux. I thought that what was to be
> deprecated was the method of binding a raw character device to a block
> device using the 'raw'.
>
> But using IDS (recent version) on Linux (recent version) you can also
> skip that and simply point your chunk to the block device.
>
> Jim
>
> On Thu, Sep 11, 2008 at 11:40 AM, Art Kagel <art.kagel@gmail.com> wrote:
> > Not yet. Linus is still pressing to get rid of RAW, but it lives on.
> >
> > Art
> >
> > On Thu, Sep 11, 2008 at 10:35 AM, Fernando Nunes
> <domusonline@gmail.com>wrote:
> >
> >> On Linux? As far as I know, cooked with DIRECT_IO
> >> Raw devices aren't deprecated on Linux?
> >>
> >> On Thu, Sep 11, 2008 at 3:29 PM, G K <ganeshkumarr@hcl.in> wrote:
> >>
> >> > Hi All,
> >> >
> >> > I have an IDS 11.1 running on a quad core processor with RHEL 5.1 and
> a
> >> > hard
> >> > disk capacity of 80 GB.
> >> >
> >> > My database details:
> >> >
> >> > Root dbspace - 2.5 GB
> >> > Dbspace 1 - 2.5 GB [ this contains the database]
> >> > Maximum database size can go up to 537 MB only.
> >> > My application requires periodic backup.
> >> >
> >> > I have been trying to figure out which would be suit my application -
> Raw
> >> > partition or Cooked File system.
> >> >
> >> > Kindly help me out in evaluating the same for my application in terms
> of
> >> > performance and access and response times.
> >> >
> >> > thanks and regards,
> >> > g k
> >> >
> >> >
> >> >
> >> >
> >>
> >>
> >
>
> *******************************************************************************
> >> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >> >
> >> >
> >>
> >> --
> >> --
> >> Fernando Nunes
> >> Portugal
> >>
> >> http://informix-technology.blogspot.com
> >> My email works... but I don't check it frequently...
> >>
> >>
> >>
> >>
> >
>
> *******************************************************************************
> >> Forum Note: Use "Reply" to post a response in the discussion forum.
> >>
> >>
> >
> > --
> > Art S. Kagel
> > Oninit (www.oninit.com)
> > IIUG Board of Directors (art@iiug.org)
> >
> > Disclaimer: Please keep in mind that my own opinions are my own opinions
> and
> > do not reflect on my employer, Oninit, the IIUG, nor any other
> organization
> > with which I am associated either explicitly or implicitly. Neither do
> those
> > opinions reflect those of other individuals affiliated with any entity
> with
> > which I am affiliated nor those of the entities themselves.
> >
> >
> >
>
> *******************************************************************************
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> >
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--
Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)

Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do those
opinions reflect those of other individuals affiliated with any entity with
which I am affiliated nor those of the entities themselves.

Messages In This Thread

• Raw Partition Vs Cooked FileSystem
  G K -- Thursday, 11 September 2008, at 10:29 a.m.
  • RE: Raw Partition Vs Cooked FileSystem
    Lello, Nick -- Thursday, 11 September 2008, at 10:33 a.m.
  • Re: Raw Partition Vs Cooked FileSystem
    Fernando Nunes -- Thursday, 11 September 2008, at 10:35 a.m.
    • Re: Raw Partition Vs Cooked FileSystem
      Art Kagel -- Thursday, 11 September 2008, at 11:40 a.m.
      • Re: Raw Partition Vs Cooked FileSystem
        Jim Tranny -- Thursday, 11 September 2008, at 2:24 p.m.
        • Re: Raw Partition Vs Cooked FileSystem
          Fernando Nunes -- Thursday, 11 September 2008, at 2:47 p.m.
        • Re: Raw Partition Vs Cooked FileSystem
          Art Kagel -- Thursday, 11 September 2008, at 3:36 p.m.
  • Re: Raw Partition Vs Cooked FileSystem
    Art Kagel -- Thursday, 11 September 2008, at 11:38 a.m.

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