[linux-lvm] lvm on a single big partition or just a single big partition?
Marian Csontos
mcsontos at redhat.com
Fri Jun 5 08:00:00 UTC 2009
Zhengquan Zhang wrote:
> On Wed, Jun 03, 2009 at 02:42:29PM -0400, Stuart D. Gathman wrote:
>
>> On Wed, 3 Jun 2009, Zhengquan Zhang wrote:
>>
>>
>>> For one harddrive I often create a /boot parition that is not lvm and
>>> create a huge partition on the rest of the harddrive for PV of lvm. Now
>>> I am thinking what is the difference between doing partition like this
>>> and just a single big partition without lvm?
>>>
>> With LVM, you can create many logical volumes. If you only ever create one
>> logical volume that fills the entire PV, and you aren't spanning drives
>> (multiple PVs) or mirroring, then LVM is not doing anything for you.
>>
Not at the moment, but the moment you run out of space and decide to add
another drive, it will save you a lot of trouble moving all your
partitions around...
> That is what I am doing, so I am not fully utilizing lvm. another
> question, is it advisable to create on pv for one harddrive?
>
>
Yes, it is the right way. Having 2 PVs on single drive offer no benefit
I can think of, and actually it is a step back - you can not share "free
space" between PVs, thus it is a way to simulate old fashioned partitions.
>> Even with just one LV, leave some space for a snapshot. Then you can
>> take more consistent backups by creating a snapshot of your main LV
>> and backing that up instead. Put your swap space in LVM as well.
>>
>
> Thanks for pointing out this. I never thought of leaving space for
> snapshot. and the swap too, why it is good to put swap in lvm?
>
>
I think most of installers do not think of it neither (unless you
partition you disk yourself, which is not so difficult, but may be a bit
scary for newbies) - I would like an install option "leave N% of created
PV free and use only the rest now".
>> One reason to create multiple LVs is for virtual machines. If you
>> run Xen, VMWare, or other virtual machine, then each virtual machine
>> should have its own LVs for disk drives. This is more efficient
>> than using a filesystem file for a virtual disk.
>>
>
> Oh really, I never thought about this, so virtual machine can directly
> use lv for the as their filesystem?
>
>
>> PS. I wonder if Grub will ever support LVM? Does LILO work with LVM?
>>
>
> As I know, LILO does, buy anyway we've got separate /boot.
>
> Thanks a lot Stuart, it helped me a lot,
>
>
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