Quick question

[David Smith_28]

Why do all root logical volumes have the contiguous option set to yes. Is this mandatory. What is the reasoning behind this?
Thanks in advance.

[Pete Randall]

David,

It's mandatory for /stand and swap. The others do not have to be contiguous.


Pete

[Pete Randall]

David,

Oh - and the reason is so the boot loader knows where to find things.


Pete

[Marco Santerre]

It is not a mandatory thing except for one or two.. If I remember correctly .. you need to have /stand contiguous and maybe your swap space.

[John Carr_2]

HP recommend root stand and swap to be contigous . The boot loader needs to know where to start reading the kernel from on the disk and be able to continue to read it sequentially.

John.

[Sridhar Bhaskarla]

Hi,

root is also to be contiguous. In fact all the logical volumes that appear in lvlnboot are to be contiguous.

-Sri

[Leif Halvarsson_2]

Hi,
Check the man page for lvlnboot. The following volumes need to be contiguos:

/
/stand
swap
dump

[Pete Randall]

Sorry, David - I missed on / - it should be contiguous as well. In a normal installation, the other lvols end up being "strict" but not "contiguous", by the way.


Pete

[Chris Wilshaw]

As others have stated, some of the volumes have to be contiguous.

The others are all contiguous as a default, because the installation process takes the next free set of extents when the volume is created.

If you were to later extend one of the filesystems (/home for example), the Allocation marker changes

On one of our systems, we created a 100MB home filesystem, and later extended this to 200MG. As you can see, Allocation is now listed as "strict", not "strict/contiguous"

--- Logical volumes ---
LV Name /dev/vg00/lvol4
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 200
Current LE 50
Allocated PE 100
Stripes 0
Stripe Size (Kbytes) 0
Bad block on
Allocation strict
IO Timeout (Seconds) default

[Sridhar Bhaskarla]

I missed the reason.

My understanding is that the kernel loads the LVM related drivers. So, prior to loading of the kernel there is no way for the boot process to find the non-contiguous blocks as it wouldn't understand the LVM structure.

-Sri