Extending of / impaired by contiguous alloc policy

[Ralph Grothe]

Hi,

I guess this will be easy for many of you to answer.

I fear the size of the root filesystem / will be far too small.
It is "only" 140 MB (must have been the default size for / of the OS installation routine).
OK, you can argue that nothing goes into / as there are seperate filesystems for /var /usr /opt etc.
But I already had accidentally filled up / to 100% when doing things as root :-(
To prevent from this happening again I would like to increase the size of / to at least 250 MB.
To do it comfortably I also installed OnlineJFS ;-)
But when I tried to extend the LV of / I had to realize that it obviously was createted with strict *and* contiguous allocation policy (I think the OS installation program here again was the culprit) :-(
Having a look at /dev/vg00/lvol4 (i.e. LV of /) I can see that the allocated PEs span from 0405-0439 = 35 PE * 4 MB = 140 MB.
Inspecting the next LV (which carries /tmp) I am relieved to realize that this one isn't marked contiguous (only strict).
/tmp's PEs span from 0440 - 0489.
So I have the sneaking faith that I could maybe reorganize /tmp's (or lvol5's) PEs to free up space in its beginnig PEs to enable the extension of lvol4 (i.e. /).
Is ist possible with the fsadm_vxfs tool to defragment /tmp so that space is deallocated from its start rather than its end.
Or what else can I do to finally increase / ?

Regards
Ralph

[Steven Sim Kok Leong]

Hi,

>> To prevent from this happening again I would like to increase the size of / to at least 250 MB.

If I were you, I would create separate filesystem(s) for those accidental pieces of data, and subsequently move the files from / to the new filesystem.

Increasing / for accidental data can only be a workaround, not a solution.

Hope this helps. Regards.

Steven Sim Kok Leong

[Vijeesh CTK]

hi
just go thru this...


How do I extend (enlarge) the root partition which is located on a logical volume, the problem being that you can't umount the root partition.

Here are 3 solutions to this commonly asked problem.

Solution 1:



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One can purchase HP IgniteUX which will also do the job, alas after paying money for this product.

Solution 2:



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Remove all things that are not needed on the root partition so you create additional space, e.g. clean up /tmp, symlink various files and/or directories, etc and create the space you need in this way.

Solution 3:



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If you are using LVM there is a work around to extend the root LV.
Boot the system in single user mode and extend the root using the lvextend command and it will extend the root logical volume.

Make sure that the space to extend the root LV is available in the same disk as continuous physical extents because the root volume allocation poicy must be contigous.

If the adjacent physical extents are occupied by any other LV move that logical volume to some other disk using pvmove command.
#pvmove -n /dev/vg00/lvolx /dev/dsk/c0txd0 /dev/dsk/c0txd0

Shutdown the machine and interrupt the normal boot process by pressing any key if it is a S800 system and if it is S700 use "esc" key.

From the boot admin prompt type boot pri isl you will get the isl prompt
ISL> hpux -lm

This will take you to the logical volume maintanence mode. Don't try to mount any logical volume and don't switch to multiuser mode or a different runlevel.

The root LV will now be mounted on /dev/root instead of /dev/vg00/lvolx

Now you can execute the extendfs command on the root logical volume:
# extendfs -F hfs /dev/vg00/rlvolx

Note down the alternate superblock locations and reboot the macine using
#reboot -n -------------- DONT MISS THIS STEP.
This will cause the system to not sync the old superblock back to the filesystem and damage it.

When you boot the system normally now you will get all the allocated space for the root filesystem.

Now you will notice that the root volume is still mounted on /dev/root rather than /dev/vg00/lvolx. To correct this you remove the /etc/mnttab and you will find bdf now displays the correct logical volume.


Regards,

Vijeesh CTK

[Ken Burke]

Hi,

The only supported way to extend the / filesystem is to do some form of re-installation. There are a few old procedures out there which attempt to extend / without re-installing but most of them stopped working from hpux 10.20 and above - there is a very good chance that your system will no longer boot if you attempt to use one of these. Also your system would not be supported by HP.

Re-installing is not as hard as it used to be, the use of Ignite/UX makes it very easy to change the sizes of the first 3 logical volumes.

http://www.software.hp.com/products/IUX/index.htm

Ignite/UX is a free product.

The /tmp filesystem is normally not part of the / filesystem.

Using pvmove on the root filesystem will not work as from hpux 10.20 and above /stand/rootconf needs to know exactly where on the disc the root filesystem is, this file can not be edited.

[Volker Borowski]

Hi,

Check out with "lvdisplay -v" / "pvdisplay -v" which lvol is the physically succeding one to root.

In a standard installation, you might be lucky, that the succeding lvol to / will be swap on lvol2 ! If you have mirror ux, you might mirror this swap elsewhere and remove the lvol2 from the mirror after successfull relocation.

After this, you should be able to extend lvol1 !

If you do not have mirror ux, you might need to relocate / shrink swap manually.

Hope this helps
Volker

[Volker Borowski]

... should have read more closely.

With /tmp you will have no trouble at all!

Create a new lvol anywhere else.
Change the mountpoint in /etc/fstab.
If you are lucky, you can remount it online, but usually someone will have something open on /tmp, so you might need to reboot.
Remount the old /tmp somewhere else and copy over, what you still need and then drop it.

Of course the mirror solution works with /tmp as well !

Volker

[Bill Hassell]

Extending a logical volume with a filesystem requires un-mounting the lvol. Then use lvextend and extendfs. If you have the optional product Online JFS (hint: swlist -l bundle | grep -i JFS) then you can do this without unmounting.

Just a note: Ignite/UX is free, not purchased. Get a copy from software.hp.com

Also, since root is the culprit, the better solution (rather than making / = 250 megs) is to move root's $HOME. It should never be in / anyways for a lot of reasons, so it could be moved to /home/root as a possibility.

The 140 megs for root is fine since the only directories that belong there are /etc/, /dev and /sbin. Be careful of unknown applications or tar/cpio tapes that forcefully store data in the wrong place.

[Ralph Grothe]

Bill (and others),

as I wrote, I ave installed OnlineJFS, so there will be no need for me to unmount any filesystem, because a mere

# fsadm -b $((*1024)) /

would suffice.

About root's $HOME.

Yes, I agree that it would be better to place it on another filesystem.
So far I only created a different home for root (viz. /root) but it is still in the same filesystem of /.
Considering now that there isn't much that root would need from his $HOME while working in single user or maintenance mode I will move it to /home/root.
Maybe I should at least do an mkdir /home/root while the /home filesystem isn't mounted, only to make sure that a login of root in maintenance mode will cause no trouble.