Re: Using swapoff command on hd6

From: James Jackson (James.Jackson@MAIL.STATE.AR.US)
Date: Mon Nov 24 2003 - 12:45:12 EST


Here's an AIX Tech Tip from IBM:
(https://techsupport.services.ibm.com/server/aix.techTips, filter
"reduce hd6")

*** Procedure to reduce default paging space AIX version before 5.1 ***

1. First check if your paging space is mirrored.

   lslv -m hd6

If it is mirrored, then you will need to break the mirror. For example:

   lslv -m hd6
   PV1 PV2
   hdisk0 hdisk1
   rmlvcopy hd6 1 hdisk1
   lslv -m hd6 (Now it should only show one copy)
   PV1
   hdisk0

2. Determine how many paging space logical volumes exist on your system.
Enter:

      lsps -a

If there is more than one paging space in rootvg, note their names
(listed in the Page Space column) and go to Step 4.

If there is just one paging space in rootvg (it will be named hd6),
continue with Step 3.

3. Check how many free physical partitions (PPs) are available. Enter:

   lsvg -p rootvg

Create a paging space to use temporarily with the following command. X
is a number between 1 and the total number of free PPs shown in the lsvg
output.

   mkps -s X -a rootvg

Run lsps -a again and note the name of the new paging space (probably
paging00).

4. Change the characteristics of the default paging space (hd6) so that
it is not active at the next reboot. Enter:

   chps -a n hd6

5. Open the file /sbin/rc.boot for editing.

   a. You will find a line reading swapon /dev/hd6.
   b. Change that to swapon /dev/pagingXX, where XX is the number of one
of the paging spaces found in Step
      1, or the number of the new paging space created in Step 2.

6. Determine which disk is the boot disk with the lslv command. The boot
disk will be shown in the PV1 column of the lslv output.

   lslv -m hd5

WARNING: Do not proceed further if the system is a /usr client, diskless
client, or dataless client.

7. Now, run the bosboot command, using the hdisk# determined in Step 5.
Enter:

   bosboot -a -d /dev/hdisk#

8. The system needs to be rebooted in order to inactivate the hd6 paging
space. Enter:

   shutdown -Fr

9. The default dump device is set to hd6. hd6 cannot be removed while it
is the dump device. Check the dump device. Enter:

   sysdumpdev -l

If the primary or secondary dump device is set to hd6 then reset the
pointer. Enter:

   sysdumpdev -P -p /dev/sysdumpnull

10. Because certain scripts are currently hard-coded to activate
/dev/hd6, it is recommended to create the new paging space under the
same name. Remove hd6 and create a new hd6 of smaller size, with the
following commands (<PS size in logical partitions> is the number of LPs
to allocate to hd6):

   rmps hd6
   mklv -y hd6 -t paging rootvg <PS size in logical partitions>

11. Open the file /sbin/rc.boot for editing.

    Change the swapon line back to swapon /dev/hd6.

12. Run:

    lsps -a

to see if hd6 is marked to be automatically swapped on at boot time.
This is determined by a y under the auto column for hd6. If an n is
under the auto column, run:

    chps -a y hd6

to change the characteristics of the default paging space.

13. Run the bosboot command, using the hdisk# determined in Step 5.

    bosboot -a -d /dev/hdisk#

14. If a temporary paging space was not created, this is the end of the
procedure. Otherwise, continue with the following steps.

15. Change the characteristics of the temporary paging space (which is
assumed to be paging00 in these steps), so that it is not active at the
next reboot. Enter:

    chps -a n paging00

16. The system needs to be rebooted in order to deactivate the temporary
paging space. Enter:

    shutdown -Fr

17. Remove the temporary paging space. Enter:

    rmps paging00

18. If the dump device was changed in Step 8 then reset the dump
pointer. Enter:

    sysdumpdev -P -p /dev/hd6

19. If you broke the mirror to hd6 in Step 1, then replace the mirrored
copy.

    For example:

    mklvcopy hd6 2 hdisk1
    lslv -m hd6
    PV1 PV2
    hdisk0 hdisk1

*** Procedure to reduce default paging space AIX version 5.1 or above
***

1. First check if your paging space is mirrored.

   lslv -m hd6

If it is mirrored, then you will need to break the mirror. For example:

   lslv -m hd6
   PV1 PV2
   hdisk0 hdisk1
   rmlvcopy hd6 1 hdisk1
   lslv -m hd6 (Now it should only show one copy)
   PV1
   hdisk0

2. Check if you have APAR IY19145 installed.

   instfix -ik IY19145

If this APAR is not installed, the system may crash when reducing paging
space with AIX 5.1.

3. Reduce default paging space hd6.

   chps -d <number of logical partitions> hd6

4. If you broke the mirror to hd6 in Step 1, then replace the mirrored
copy.

   For example:

   mklvcopy hd6 2 hdisk1
   lslv -m hd6
   PV1 PV2
   hdisk0 hdisk1

Regards,

James Jackson

-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
Green, Simon
Sent: Monday, November 24, 2003 11:23 AM
To: aix-l@Princeton.EDU
Subject: Re: Using swapoff command on hd6

I'm aware of how to mess with bos.boot: it's only swapoff/rmps I'm
interested in at this time. New tools, so I'm just seeking the
assurance
that somebody else has done it, and nothing keeled over. The ultimate
objective is to shrink hd6 as painlessly as possible.

Simon Green
Altria ITSC Europe Ltd

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Please post all follow-ups to the list.

> -----Original Message-----
> From: Bob Booth - UIUC [mailto:booth@UIUC.EDU]
> Sent: 24 November 2003 16:53
> To: aix-l@Princeton.EDU
> Subject: Re: Using swapoff command on hd6
>
>
> I don't believe there is a restriction. You can also go into
> /sbin/rc.boot
> and edit the swapon hd6 line to what ever swapspace you want. Just
> remember to bosboot after editing the file. I have used this
> procedure
> a few times to get rid of hd6.
>
> Is this the qustion your asking?
>
> bob
>
> On Mon, Nov 24, 2003 at 05:34:39PM +0100, Green, Simon wrote:
> > Is there any restriction on using swapoff and rmps with /dev/hd6?
> > Obviously the system expects hd6 to exist at boot time, so
> you'd have to
> > re-create it before re-booting.
> >
> > Simon Green
>



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