[linux-lvm] partition strategy

[linux-lvm] partition strategy

[Arshavir Grigorian]

Hi,

This is my first post, so please bear with me.

I have 2 free disk areas 230G and 231G. I hoping to take advantage of 
RAID-0.

Is it better to create 3 partitions 2 x230G + 1G - create a striped LV 
over the first 2, then add the third to the volume group, then extend 
the LV over to the new 1G extension (since LVM2 allows extending striped 
lv-s). And if so, does the non-striped area get used as a last resort 
(after the striped area is completely full)?

OR

Is it better to create 2 paritions 230G and 231G, put both in a vg, 
create a striped lv and lvm will take care of striping to the 230G mark, 
then writing linearly afterwards.

TIA for any advice.



Best,

Arshavir

[linux-lvm] Re: partition strategy

[Arshavir Grigorian]

Arshavir Grigorian wrote:

> Hi,
>
> This is my first post, so please bear with me.
>
> I have 2 free disk areas 230G and 231G. I hoping to take advantage of 
> RAID-0.
>
> Is it better to create 3 partitions 2 x230G + 1G - create a striped LV 
> over the first 2, then add the third to the volume group, then extend 
> the LV over to the new 1G extension (since LVM2 allows extending 
> striped lv-s). And if so, does the non-striped area get used as a last 
> resort (after the striped area is completely full)?
>
> OR
>
> Is it better to create 2 paritions 230G and 231G, put both in a vg, 
> create a striped lv and lvm will take care of striping to the 230G 
> mark, then writing linearly afterwards.
>
> TIA for any advice.
>
>
>
> Best,
>
> Arshavir
>
Hi,

I mailed the above message about a week ago and there have not been any 
reponses.
I am wondering whether there is a development list where I might have a 
better chance of getting an answer to my question (the HOWTO page did 
not mention any dev lists, so I am not sure).
Many thanks.


Arshavir

Re: [linux-lvm] Re: partition strategy

[Stephen Boulet]

On Wednesday 01 September 2004 04:09 pm, Arshavir Grigorian wrote:

> Arshavir Grigorian wrote:


> > Is it better to create 3 partitions 2 x230G + 1G - create a striped LV
> > over the first 2, then add the third to the volume group, then extend
> > the LV over to the new 1G extension (since LVM2 allows extending
> > striped lv-s). And if so, does the non-striped area get used as a last
> > resort (after the striped area is completely full)?

I don't have the expertise to know for sure but that makes sense to me. I 
would just make 3 partitions -- you can always just save the 1GB partition 
for something else -- swap or a backup partition. 

-- 

Stephen      

If your desktop gets out of control easily,
you probably have too much stuff on it that
doesn't need to be there.
         Donna Smallin, "Unclutter Your Home"

Re: [linux-lvm] Re: partition strategy

[Alasdair G Kergon]

On Wed, Sep 01, 2004 at 05:09:52PM -0400, Arshavir Grigorian wrote:
> >Is it better to create 3 partitions 2 x230G + 1G 
> >OR
> >Is it better to create 2 paritions 230G and 231G, put both in a vg, 

The VG contains the same space in both cases so do the simplest
ie the first option.  In both cases you'll need to run lvcreate for
460G followed by lvextend for 1G.

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] Re: partition strategy

[Arshavir Grigorian]

Alasdair G Kergon wrote:

>On Wed, Sep 01, 2004 at 05:09:52PM -0400, Arshavir Grigorian wrote:
>  
>
>>>Is it better to create 3 partitions 2 x230G + 1G 
>>>OR
>>>Is it better to create 2 paritions 230G and 231G, put both in a vg, 
>>>      
>>>
>
>The VG contains the same space in both cases so do the simplest
>ie the first option.  In both cases you'll need to run lvcreate for
>460G followed by lvextend for 1G.
>
>Alasdair
>  
>

Thanks for the response.
For some reason even the first option does not work.
I created 3 partitions, added the 2 same sized ones to a vg, created a 
striped lv, then extended the vg to include the third small partition. 
After this I tried extending the lv to the new partition, but got the 
error below. Could you, please tell me what I am doing wrong? TIA.

Arshavir

casals:~# vgdisplay
  --- Volume group ---
  VG Name               vg00
  System ID            
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               463.60 GB
  PE Size               4.00 MB
  Total PE              118682
  Alloc PE / Size       0 / 0  
  Free  PE / Size       118682 / 463.60 GB
  VG UUID               PyRda0-g9mC-LxrH-txvE-CKb6-jP6T-Ou103y

casals:~# lvcreate -i 2 -I 8 -l 118682 vg00

casals:~# vgextend vg00 /dev/hdc3
  Volume group "vg00" successfully extended

casals:~# vgdisplay
  --- Volume group ---
  VG Name               vg00
  System ID            
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               464.12 GB
  PE Size               4.00 MB
  Total PE              118816
  Alloc PE / Size       118682 / 463.60 GB
  Free  PE / Size       134 / 536.00 MB
  VG UUID               PyRda0-g9mC-LxrH-txvE-CKb6-jP6T-Ou103y
  
casals:~# lvextend -l +134 /dev/vg00/lvol0 /dev/hdc3
  Using stripesize of last segment 8KB
  Extending logical volume lvol0 to 464.12 GB
  Insufficient allocatable extents suitable for parallel use for logical 
volume lvol0: 118816 required

Re: [linux-lvm] Re: partition strategy

[Alasdair G Kergon]

> >>>Is it better to create 3 partitions 2 x230G + 1G 
> >>>Is it better to create 2 paritions 230G and 231G, put both in a vg, 

> >ie the first option.  
I meant the second option:-)

> Could you, please tell me what I am doing wrong? TIA.
 
> casals:~# lvextend -l +134 /dev/vg00/lvol0 /dev/hdc3
>  Using stripesize of last segment 8KB
>  Insufficient allocatable extents suitable for parallel use for logical 
> volume lvol0: 118816 required

If you don't specify the stripe settings, lvextend uses whatever
the last segment of the LV you're extending uses i.e. 2 stripes in 
this case.  So you need to specify -i1 to add a new segment with
just one stripe.

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] Re: partition strategy

[Arshavir Grigorian]

Alasdair G Kergon wrote:

>>>>>Is it better to create 3 partitions 2 x230G + 1G 
>>>>>Is it better to create 2 paritions 230G and 231G, put both in a vg, 
>>>>>          
>>>>>
>
>  
>
>>>ie the first option.  
>>>      
>>>
>I meant the second option:-)
>
>  
>
>>Could you, please tell me what I am doing wrong? TIA.
>>    
>>
> 
>  
>
>>casals:~# lvextend -l +134 /dev/vg00/lvol0 /dev/hdc3
>> Using stripesize of last segment 8KB
>> Insufficient allocatable extents suitable for parallel use for logical 
>>volume lvol0: 118816 required
>>    
>>
>
>If you don't specify the stripe settings, lvextend uses whatever
>the last segment of the LV you're extending uses i.e. 2 stripes in 
>this case.  So you need to specify -i1 to add a new segment with
>just one stripe.
>
>Alasdair
>  
>
Many thanks. It all makes sense now.
The way I got it working is just creating 2 partititions, getting the 
number of extends from the smaller partition, creating a striped lv with 
that paritition count, then extending it to the remaining the extents as 
with a single stripe.


Arshavir