[linux-lvm] Different PV on the same raid array

[linux-lvm] Different PV on the same raid array

[Cédric Lemarchand]

Hello,

To bypass the DOS MBR 2TB limits, i plan to use LVM to create on the
same raid array some "small" PV (< 2TB)  that will be in the same big VG
(> 2TB).

First, am i planning ugly thing ? is the GPT alternative a better way ?

Secondly, I dont know how LVM use PVs within a VG, but for performances
issues, i would like that LVM use 1 PV first and then the second when
the first come full  (not both at the same time).
Maybe LVM do that by default, or do i need some option ? (i saw
"--contiguous" in the lvcreate man pages, but dont know exactly what
this option does ... )


Thx

Cédric

Re: [linux-lvm] Different PV on the same raid array

[Ray Morris]

> To bypass the DOS MBR 2TB limits, i plan to use LVM to create on the
> same raid array some "small" PV (< 2TB)  that will be in the same big
> VG (> 2TB).
> 
> First, am i planning ugly thing ? is the GPT alternative a better
> way ?

   If you're not booting from the array, just make the array 
the PV.  Once you're past the BIOS boot, there's little reason
to have partitions at all since you're using LVM to divide the 
storage into appropriate volumes.  If you are booting from it
and therefore need partitions, GPT is the new standard for 
partitions.

> i would like that LVM use 1 PV first and then
> the second when the first come full  (not both at the same time).
> Maybe LVM do that by default, or do i need some option ? (i saw
> "--contiguous" in the lvcreate man pages, but dont know exactly what
> this option does ... )

  I think it does that by default, subject to certain other contraints
such as not putting both halves of a mirrored LV on the same PV.
-- 
Ray Morris
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On Thu, 24 Feb 2011 11:51:26 +0100
Cédric Lemarchand <cedric.lemarchand@ixcore.com> wrote:

> Hello,
> 
> To bypass the DOS MBR 2TB limits, i plan to use LVM to create on the
> same raid array some "small" PV (< 2TB)  that will be in the same big
> VG (> 2TB).
> 
> First, am i planning ugly thing ? is the GPT alternative a better
> way ?
> 
> Secondly, I dont know how LVM use PVs within a VG, but for
> performances issues, i would like that LVM use 1 PV first and then
> the second when the first come full  (not both at the same time).
> Maybe LVM do that by default, or do i need some option ? (i saw
> "--contiguous" in the lvcreate man pages, but dont know exactly what
> this option does ... )
> 
> 
> Thx
> 
> Cédric
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Different PV on the same raid array

[Cédric Lemarchand]

Le 24/02/11 14:04, Ray Morris a écrit :
>> To bypass the DOS MBR 2TB limits, i plan to use LVM to create on the
>> > same raid array some "small" PV (< 2TB)  that will be in the same big
>> > VG (> 2TB).
>> > 
>> > First, am i planning ugly thing ? is the GPT alternative a better
>> > way ?
>    If you're not booting from the array, just make the array 
> the PV.  Once you're past the BIOS boot, there's little reason
> to have partitions at all since you're using LVM to divide the 
> storage into appropriate volumes.  If you are booting from it
> and therefore need partitions, GPT is the new standard for 
> partitions.
Ok, i am booting on but on a different partition, so i'll need to use
GPT or maybe split my array in two parts, one small for OS (using MBR)
and second for DATA (without partitions, or with GPT).
>> > i would like that LVM use 1 PV first and then
>> > the second when the first come full  (not both at the same time).
>> > Maybe LVM do that by default, or do i need some option ? (i saw
>> > "--contiguous" in the lvcreate man pages, but dont know exactly what
>> > this option does ... )
>   I think it does that by default, subject to certain other contraints
> such as not putting both halves of a mirrored LV on the same PV.

Thx for this precious informations.


Cédric