Re: [linux-lvm] lvm and md

[Peter Yao <peter@exavio.com.cn>]

Jon Bendtsen wrote:
> Peter Yao wrote:
> 
>>Should we build lvm volumns on top of soft raid(md) or build md on top
>>of lvm volumns?
>>I prefer to build md on top of lvm volumns because lvm can hide the
>>hardware details from md. Just want to know how do you think about this.
>>Or any URLs? Thanks.
> 
> 
> why would you need to hide the hardware details from md ?
I am using some hot-plugging disks and their device number may change 
after reboot. For example, if i build md with /dev/sda and /dev/sdb, 
after reboot md may cannot start because the two disks' device name 
change to /dev/sdc and /dev/sdd. If i build md on top of lvm this 
problem is avoided. Can you give me some advice for this issue?

> The way i do it is to md 2 disks together into a pair, and
> then pvcreate it and add it to my VG. That way i can get 
> more and more disks into the system. I have thought about
> creating 2 VG's, and then run md ontop of that, but it's more
> work, as you would have to resize 2 LV's, and besides, a harddisk
> failure might trash one of your VG's. Meaning more repair work.
> 
> 
> 
> JonB
> 
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> 
> 
> 


-- 
Peter Yao