IDS Forum

Re: is there a way to find out the physical device

Posted By: Art Kagel
Date: Thursday, 16 June 2011, at 2:34 p.m.

In Response To: is there a way to find out the physical device fil (jim-cramer@uiowa.edu)

Unfortunately, no. Informix only stored the links you provide, it does not
follow the links to their core names at all, it depends on the OS to
maintain and promote the links.

HOWEVER, there is one way. Use dd piped to od -x to read the first few
pages (so 2K each if you used the default pagesize or whatever the pagesize
of the dbspaces were) of each chunk's physical device. The first six bytes
of each page have the chunk number encoded. So on my server for chunk #1:

$ dd if=/opt/informix/infmx.11.70.FC1B7/dbspaces/rootdb.1.chunk bs=2k
count=2|od -x
2+0 records in
2+0 records out
4096 bytes (4.1 kB) copied, 0.00441886 s, 927 kB/s
0000000 *0000 0000 0001* 9600 0003 1800 0130 06c0
0000020 0000 0000 0000 0000 4249 204d 6e49 6f66

For chunk #6:

$ dd if=/opt/informix/infmx.11.70.FC1B7/dbspaces/tempdbs1.1.chunk bs=2k
count=1|od -x
1+0 records in
1+0 records out
2048 bytes (2.0 kB) copied, 7.7661e-05 s, 26.4 MB/s
0000000 *0000 0000 0006* 492e 0000 1800 0018 07e4
0000020 0000 0000 0000 0000 0000 0000 0000 0000

Armed with the chunk numbers you should be able to recreate the links.

Art S. Kagel
Advanced DataTools (www.advancedatatools.com)
Blog: http://informix-myview.blogspot.com/

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

On Thu, Jun 16, 2011 at 2:23 PM, jim-cramer@uiowa.edu
<jim-cramer@uiowa.edu>wrote:

> Help!
>
> 11.70.FC1 on Linux SUSE 11 SLES
>
> After setting up a 11.7 IDS instance and creating a bunch
> of Logical Volumes, creating Symbolic Links in /dev that
> pointed to the block device files that the LV Manager created,
> changing the ownership and permission on these device files
> appropriately, creating dbspaces from the chunks *using the
> Symbolic Link pathnames* to the chunk device files,
> I found out that when the Linux system was rebooted all
> of the Symbolic Links for my Informix Chunks were deleted
> from /dev (and also that the ownership and permissions for the
> chunk devices files had reverted to my pre-configured state).
>
> I need to re-create the symbolic links for the chunks, in
> some non-system directory I assume.
>
> The names of the symbolic links that I created indicated
> what dbspace the each chunk belonged to. I have those link names in
> my $INFORMIXDIR/etc/oncfg_servername.0 file as the pathname
> to each Chunks.
>
> UNFORTUNATELY, the names that I gave the Logical
> Volumes, and hence the names of the devices files created
> for the LVs/Chunks, did not indicate which Chunk/DBSpace
> each was created for (i.e.: I used a systematic pattern vol01,
> vol02, vol02,...)
>
> So, I need a way to find out the physical device file pathname
> that each of the symbolic links had pointed to, so that I
> can recreate the links correctly.
>
> OR
>
> since those links have been blown away by the OS and the instance
> is down, is there a file somewhere where I would find this info?
>
> Or
>
> is there an Informix Utility that can be run against a down instance
> that would list out the chunks that had been created for that instance
> along with the physical device file pathname for each?
>
> Any information or ideas would be appreciated.
>
> Thanks,
>
> Jim Cramer
> Univ of Iowa
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--bcaec5016349fe9e0304a5d882f3

Messages In This Thread

• is there a way to find out the physical device fil
  jim-cramer@uiowa.edu -- Thursday, 16 June 2011, at 2:23 p.m.
  • Re: is there a way to find out the physical device
    Art Kagel -- Thursday, 16 June 2011, at 2:34 p.m.
    • RE: is there a way to find out the physical de....
      jim-cramer@uiowa.edu -- Thursday, 16 June 2011, at 5:17 p.m.
      • Re: is there a way to find out the physical de....
        Art Kagel -- Thursday, 16 June 2011, at 6:59 p.m.
        • Re: is there a way to find out the physical de....
          jim-cramer@uiowa.edu -- Friday, 17 June 2011, at 9:41 a.m.
          • Re: is there a way to find out the physical de....
            Art Kagel -- Friday, 17 June 2011, at 10:09 a.m.
            • RE: is there a way to find out the physical de....
              jim-cramer@uiowa.edu -- Friday, 17 June 2011, at 10:57 a.m.
              • RE: is there a way to find out the physical de....
                Jamie Gedye -- Friday, 17 June 2011, at 1:16 p.m.
                • RE: is there a way to find out the physical de....
                  Cramer, James A -- Monday, 20 June 2011, at 1:43 p.m.
                  • RE: is there a way to find out the physical de....
                    Jamie Gedye -- Monday, 20 June 2011, at 3:07 p.m.
                    • RE: is there a way to find out the physical de....
                      Cramer, James A -- Monday, 20 June 2011, at 5:39 p.m.
        • RE: is there a way to find out the physical de....
          jim-cramer@uiowa.edu -- Monday, 20 June 2011, at 1:31 p.m.
          • Re: is there a way to find out the physical de....
            Art Kagel -- Monday, 20 June 2011, at 2:23 p.m.
            • RE: is there a way to find out the physical de....
              Cramer, James A -- Monday, 20 June 2011, at 2:48 p.m.
        • RE: is there a way to find out the physical de....
          jim-cramer@uiowa.edu -- Tuesday, 21 June 2011, at 1:06 p.m.
          • Re: is there a way to find out the physical de....
            Art Kagel -- Tuesday, 21 June 2011, at 1:14 p.m.
            • RE: is there a way to find out the physical de....
              Wyza, Jonathon -- Tuesday, 21 June 2011, at 1:56 p.m.
              • RE: is there a way to find out the physical de....
                jim-cramer@uiowa.edu -- Tuesday, 21 June 2011, at 2:44 p.m.
            • RE: is there a way to find out the physical de....
              jim-cramer@uiowa.edu -- Tuesday, 21 June 2011, at 2:30 p.m.
            • Re: is there a way to find out the physical de....
              rroussey@comcast.net -- Tuesday, 21 June 2011, at 6:05 p.m.
              • RE: is there a way to find out the physical de....
                jim-cramer@uiowa.edu -- Tuesday, 21 June 2011, at 7:01 p.m.

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