IDS Forum

Re: clarification on Informix on Suse Linux

Posted By: Fernando Nunes
Date: Thursday, 9 February 2017, at 9:55 p.m.

In Response To: clarification on Informix on Suse Linux (John Adamski (Work Account))

RAW devices on Linux have always been tricky.... coming and going, Linus
fighting them etc.

But this misses the point. RAW devices were used to avoid system memory
caching and avoid context switching (user vs kernel mode)
And since version 10 (with intermittent issues) we've been supporting block
devices opened with O_DIRECT flag. This translates to that you can create
your "pseudo-raw" block devices with LVM and use them with Informix as you
would do with RAW devices.
You'll get KAIO... no buffer caching and no context switch on IO.

And then again, we're possibly still missing the point... You can get this
with cooked files which are much easier to manage, don't require root
intervention etc... That's because we support DIRECT I/O (DIO) through the
ONCONFIG parameter DIRECT_IO.

So... you could do some tests.... But I doubt that a well done test will
show significant differences... If you really enjoy creating the "raw"
devices... do it with LVM and don't bother with the block/character
interface. We'll open them with O_DIRECT. On the other hand, why not try
the filesystem approach which make it more easy and manageable?

Regards.

On Thu, Feb 9, 2017 at 5:39 PM, John Adamski (Work Account) <
adamski@graceland.edu> wrote:

> Our ERP is forcing us to move from HPUX to Suse Linux and they said
> something
> I'm not sure Is 100% correct.
>
> They have said that Informix 12.1 on Suse Linux can only be installed using
> cooked file system I do not think this is 100% correct, more likely they
> only
> wish to support cooked file system. And since they recommend using virtual
> servers, coked file systems make cloning easy, but raw LUNs have to be
> detached for the cloning to be done.
>
> Am I correct that Informix 12.1 FC6 on Suse Linux 11 can handle raw or
> cooked
> file systems? The choice of which to use is the installer? I couldn't find
> anything in the documentation saying only cooked file system, but maybe I
> was
> looking at the wrong documents.
>
> John David Adamski, Sr. Network Specialist
> Graceland University, 1 Univeristy Place, Lamoni, IA 50140
> adamski@graceland.edu
> 641-784-5267
>
>
> ************************************************************
> *******************
> 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...

--001a11475394a4feb80548243aa5

Messages In This Thread

• clarification on Informix on Suse Linux
  John Adamski (Work Account) -- Thursday, 9 February 2017, at 12:39 p.m.
  • Re: clarification on Informix on Suse Linux
    Spokey Wheeler -- Thursday, 9 February 2017, at 12:46 p.m.
  • Re: clarification on Informix on Suse Linux
    Art Kagel -- Thursday, 9 February 2017, at 1:08 p.m.
    • Re: clarification on Informix on Suse Linux
      david@smooth1.co.uk -- Thursday, 9 February 2017, at 1:43 p.m.
  • Re: clarification on Informix on Suse Linux
    Fernando Nunes -- Thursday, 9 February 2017, at 9:55 p.m.
    • Re: clarification on Informix on Suse Linux
      JACOBO BALBUENA -- Friday, 10 March 2017, at 5:51 a.m.

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