[linux-lvm] cannot extend lv

[Rainer.Lay at informatik.uni-erlangen.de]

My idea was not to make a 4 stripe set with 4 PV, but a 2 stripe set:

stripe1: aaaaaaaaabbbbbb
stripe2: cccccccccdddddd

so if PV a and c are full, PV b and d are used.

I would create a new lv as you suggested, but drives a and c are two 
times bigger than b and d, so I thought about the above solution.

Rainer

>> I have a vg (data) with four drives /dev/sd[b-e]1
>> I created a 2 stripes lv (data1) with sd[bc]1
>                 ^^^^^^^
> 
> You cannot extend striped lvs onto new pvs. Even on the
> same physical hardware.  Once you have striped it, you are
> tied to the pvs used.
> 
> If you think about it, this makes sense, as otherwise you
> have some stripes containing more data than others.  In fact,
> as soon as the smallest pv is full, you will not be able to
> extend the lv, even if there is room in the other pvs.
> 
> If you want to have the filesystem striped over all the disks, you
> will need to create a new lv which is striped across them all,
> transfer the data to it, delete the old lv and then extend the
> new one.
> 
> Backups highly recommended.
> 
> Michael