IDS Forum

RE: Are there issues when using RAW dbspaces o....

Posted By: jim-cramer@uiowa.edu
Date: Thursday, 29 July 2010, at 9:55 a.m.

In Response To: RE: Are there issues when using RAW dbspaces o.... (Wyza, Jonathon)

Hi again Jonathon,

It is my understanding that SUSE Linux comes with more than
1 Logical Volume Manager.

If this is the case, can you tell me which one the concern that
you mention below applies to?

Also, one of our Sys Admins told me that at least one of the LVMs
on Linux has a built-in mechanism that I could take advantage of
to avoid the pitfall that you mention. The mechanism apparently
involves a couple levels of symbolic links for each device file.
He says that the system will dynamically change the lowest level
link for a device file at times, but that it will also update
a higher level link, whose name/path never changes, for the same device
to reflect the change in the underlying link. In other words,
if I used the highest level link for a device file in my creation
of a db chunk, the pitfall you mention would be avoided.

I don't know if this mechanism that he told me about applied to
all Logical Volume Managers provide with SUSE and will check with
him on that.

In the mean time, it would be useful if you could tell me the name
of the LVM that you know the situation you described happens with.

Thanks,

Jim

-----Original Message-----
From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Wyza,
Jonathon
Sent: Wednesday, July 28, 2010 10:21 AM
To: ids@iiug.org
Subject: RE: Are there issues when using RAW dbspaces o.... [20675]

There is a problem with the way that linux handles logical volumes with
informix. But it is easily fixable. By default the major/minor numbers for
the
logical volume devices are assigned dynamically at boot. Because of this
your
chunks could move, but informix wouldn't know where they went. You can set
the
volumes to have static device numbers to fix that problem. Again, they
don't
have to do ANYTHING.....

By and by the command would be something like this:

lvchange -M --major # --minor # "/dev/mapper/lg-lgname-lv-lvname"

Jonathon Wyza
CX & CBORD System Administrator
CX Programmer/Analyst
Administrative Computing
Bethel College
(574)-257-3381
AIM: Iamwyza
jonathon.wyza@bethelcollege.edu
==============================
SLES 11x64 & IDS 11.50.FC6

"Don't document the problem, fix it."
- Atli Björgvin Oddsson

-----Original Message-----
From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
jim-cramer@uiowa.edu
Sent: Wednesday, July 28, 2010 11:15 AM
To: ids@iiug.org
Subject: RE: Are there issues when using RAW dbspaces o.... [20673]

Jonathon,

Thank you very much for the fast response and the below info.

At 2 pm I had to do battle with the Sys Admins here and your information,
as
well as what Art has been saying all last week (and previous to that)
about
Raw db chunks and issues, helped me argue my case.

As far as what I said and was worried about in issue (1) goes, either I
misunderstand what was rattled off to me this morning in a hurry about
that or
they have changed their tune.

After talking to them, I was pretty sure that the admins, or perhaps just
one
of them, were claiming that there could be issues with the ESX server
management/system software/ utilities affecting the raw db chunks in the
VMs
that my Informix instances are in. You are right, that makes
0 sense. I thought so too at the time, but perhaps I misunderstood.
Because
now they are saying that their concern is that Linux system management
stuff,
such as YAST, within the VMs that my Informix instances are in could mess
with
my raw logical volumes used as Informix chunks. They said that they have
to
configure some things inside the VMs so that they do not do that.

I have no Linux Sys Admin experience, just HP-UX.
If you are aware of anything that is part of Linux that might be a
consideration when I use raw logical volumes, please let me know if you
get a
chance.

Thanks again for your help!

Jim

-----Original Message-----
From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
Wyza,
Jonathon
Sent: Tuesday, July 27, 2010 2:23 PM
To: ids@iiug.org
Subject: RE: Are there issues when using RAW dbspaces o.... [20663]

1) That makes 0 sense. Although you will be using raw spaces, the drives
themselves are allocated by the host for the client to use in any way it
sees
fit, just have them allocate the space on drive creation instead of when
it
needs it (just so you have sequential sectors on the discs). Raw spaces
will

work fine in a virtual environment.
2) Backing it up using their utility is silly. Use ontap or onbar.
3) Little bit? try at least 20% increase. And what sys admin overhead are
they
talking about?
4) JFS is exactly why you DON"T want cooked files. look at the thread
about
performance issue with ZFS on this board just this week to see a nice long

explanation by Art about this.

Jonathon Wyza
CX & CBORD System Administrator
CX Programmer/Analyst
Administrative Computing
Bethel College
(574)-257-3381
AIM: Iamwyza
jonathon.wyza@bethelcollege.edu
==============================
SLES 11x64 & IDS 11.50.FC6

"Don't document the problem, fix it."
- Atli Björgvin Oddsson

________________________________________
From: ids-bounces@iiug.org [ids-bounces@iiug.org] on behalf of Jim Cramer
[jim-cramer@uiowa.edu]
Sent: Tuesday, July 27, 2010 3:14 PM
To: ids@iiug.org
Subject: Are there issues when using RAW dbspaces on ID.... [20662]

HELP!

Here is another angle to the recent questions, and explanations by Art,
et.
al, regarding using RAW instead of COOKED dbspaces on IDS 11.5 running on
Linux.

For reasons cited by Art and the others, I (the DBA) wish to use RAW
dbspaces
when I move my instances to Linux (SUSE 11 SLES) Virtual Machines on an
ESX
Server running VMWare.

But my Sys Admins here are refusing to allow RAW spaces and citing all
kinds
of vague, generalized reasons why, such as:

1) the "host administration utilities" will not fly right with Raw Spaces
but
will not be specific about what would go wrong. In general, my sense is
that
they feel that the Management Console and Tools for the ESX host might see
the
Raw Dbspace and, because it does not contain not a formatted filesystem,
allocate it to something on the box.

2) using raw space will not allow the VMs containing the IDS dbspaces to
be
backed up or fit into their backup strategy and backup utility.

They cannot seem to understand that a normal backup utility would not know
how
to deal with the dbspaces even if they were Cooked.

3) that the "little bit" of performance that they claim I might get with
Raw
will not pay back for the increased Sys Admin overhead.

4) that they will use a Journaled File System (along with Cooked
dbspaces) because it is more robust, fault-tolerant, comes back up quicker

after a crash, etc.

Can anybody provide me with any concrete information/experience that is
related to the above points, particularly (1) .

Does anyone know if raw dbspaces can cause problems in a Virtual Machine
on a
VMWare ESX Server.

If you have some info and have time to send it soon, that would be
appreciated
because I am about to do battle over this with our Sys Admins.

Thanks much in advance,

Jim Cramer
Database Administrator and
Applications Developer III
University of Iowa
College of Engineering
Engineering Computer Systems Support
1256 SC
Iowa City, Iowa 52245
(319)-335-5757
jim-cramer@uiowa.edu
jcramer@engineering.uiowa.edu
http://css.engineering.uiowa.edu
http://www.engineering.uiowa.edu
http://www.uiowa.edu

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Messages In This Thread

• Are there issues when using RAW dbspaces on IDS 11
  Jim Cramer -- Tuesday, 27 July 2010, at 3:14 p.m.
  • RE: Are there issues when using RAW dbspaces on ID
    Wyza, Jonathon -- Tuesday, 27 July 2010, at 3:22 p.m.
    • RE: Are there issues when using RAW dbspaces o....
      jim-cramer@uiowa.edu -- Wednesday, 28 July 2010, at 11:15 a.m.
      • RE: Are there issues when using RAW dbspaces o....
        Wyza, Jonathon -- Wednesday, 28 July 2010, at 11:20 a.m.
        • RE: Are there issues when using RAW dbspaces o....
          jim-cramer@uiowa.edu -- Wednesday, 28 July 2010, at 11:48 a.m.
        • RE: Are there issues when using RAW dbspaces o....
          jim-cramer@uiowa.edu -- Thursday, 29 July 2010, at 9:55 a.m.
          • RE: Are there issues when using RAW dbspaces o....
            Wyza, Jonathon -- Thursday, 29 July 2010, at 10:34 a.m.
            • RE: Are there issues when using RAW dbspaces o....
              jim-cramer@uiowa.edu -- Thursday, 29 July 2010, at 10:56 a.m.
  • Re: Are there issues when using RAW dbspaces on ID
    Alexandre Marini -- Tuesday, 27 July 2010, at 3:30 p.m.
    • RE: Are there issues when using RAW dbspaces o....
      jim-cramer@uiowa.edu -- Wednesday, 28 July 2010, at 11:15 a.m.
  • Re: Are there issues when using RAW dbspaces on ID
    Art Kagel -- Tuesday, 27 July 2010, at 5:59 p.m.
    • Re: Are there issues when using RAW dbspaces o....
      Fernando Nunes -- Wednesday, 28 July 2010, at 4:18 a.m.
      • Re: Are there issues when using RAW dbspaces o....
        Art Kagel -- Wednesday, 28 July 2010, at 8:48 a.m.
        • RE: Are there issues when using RAW dbspaces o....
          jim-cramer@uiowa.edu -- Wednesday, 28 July 2010, at 11:40 a.m.
          • Re: Are there issues when using RAW dbspaces o....
            Art Kagel -- Wednesday, 28 July 2010, at 5:11 p.m.
      • RE: Are there issues when using RAW dbspaces o....
        jim-cramer@uiowa.edu -- Wednesday, 28 July 2010, at 11:31 a.m.
  • RE: Are there issues when using RAW dbspaces on ID
    Andrew Lennard -- Wednesday, 28 July 2010, at 12:19 p.m.

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