Unable to extend FS.

[ankitj1983]

Dear All,

I have root FS on lvol3

Filesystem kbytes used avail %used Mounted on
/dev/vg00/lvol3 524288 516328 7960 98% /
eux091{root}#


I want to extedn this by 2G.

Currently its 500M.

Getting the below error while trying to exend it.

eux091{root}# lvextend -L 600M /dev/vg00/lvol3
Warning: rounding up logical volume size to extent boundary at size "608" MB.
lvextend: Not enough free physical extents available.
Logical volume "/dev/vg00/lvol3" could not be extended.
Failure possibly caused by contiguous allocation policy.
Failure possibly caused by strict allocation policy


##################

PE's are also available.

eux091{root}# vgdisplay vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 19
Open LV 19
Max PV 16
Cur PV 4
Act PV 4
Max PE per PV 4384
VGDA 8
PE Size (Mbytes) 16
Total PE 17496
Alloc PE 10758
Free PE 6738
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

eux091{root}# lvdisplay /dev/vg00/lvol3
--- Logical volumes ---
LV Name /dev/vg00/lvol3
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 512
Current LE 32
Allocated PE 64
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation strict/contiguous
IO Timeout (Seconds) default


Thnaks in advance.

Regards

Ankit

[Torsten.]

>> Failure possibly caused by contiguous allocation policy.
Failure possibly caused by strict allocation policy


This is true, but cannot be changed.



Recommended action is to take an ignite backup and adjust the size during restore.

[ankitj1983]

But still didt understand why i cant increase the FS

[Torsten.]

Because the LVOL must be contiguous and strict.

[Hakki Aydin Ucar]

in very simple words, root extension is not easy like other file systems due to adjacent volumes allocation policy restriction, and you have to to with ignite restoration.

[Bijeesh]

The LVs /dev/vg00/lvol1(/stand),/dev/vg00/lvol2(swap) and /dev/vg00/lvol3(/) must be contiguous which is stricred by the OS. That is why you are not able to increase the root LV.
Like Torsten mentioned,the standard procedure to increase the root lv is by ignite.Take the ignite backup and install the OS using Advanced option from where you can modify the size root lvs.

[Hakki Aydin Ucar]

Hi,

BTW, seems possible by Geoff Wild have made a site for tips and tricks: (IF YOU HAVE ONLINE JFS!)

http://www.met.ca/itrc/index.php?option=com_content&task=view&id=89&Itemid=2

[ankitj1983]

OK nOw understood why i cant increase the FS b'coz of contigous.

So why we use this option & what is the significance to use ?

[Viktor Balogh]

> So why we use this option & what is the significance to use ?

This is for performance purposes. If the data lies contiguously on the disk, the read/write head of the disk shouldn't jump back and forth during operation. This is a constraint by the OS that was designed so, and it cannot be changed. However, normally you don't need to extend the rootfs, once the system got installed. You should otherwise keep the data separate from the system files, (normally not even on a local disk but in the SAN) - this way also ensuring that you only backup the minimum system with the make_*_recovery commands.

Regards,
Viktor

[Matti_Kurkela · Accepted solution]

For the system disk, the reason for the three first LVs being contiguous is not performance. It's because the HP-UX bootloader ("hpux" or "hpux.efi") does not really understand LVM at all. For a related reason, /stand must be a HFS filesystem on PA-RISC: the "hpux" bootloader does not understand VxFS.

The HP-UX bootloader requires that the /stand filesystem, the primary swap and the root filesystem are always in this order and contiguous at the beginning of the system disk. This way the bootloader can use a very simple algorithm to find them.

This limitation is probably because the bootloader needs to be very small to fit in the boot LIF on the PA-RISC systems.

On Itanium, the EFI bootloader allows much more complex OS bootloader code to be created. In the future, HP will introduce a version of HP-UX that no longer needs to be bootable on old PA-RISC hardware, and maybe that version will eventually remove the requirement to always have the root filesystem contiguous.

MK