[Novalug] "clandestine" lvm disk move?

Kurt Yoder ktynovalug at yoderhome.com
Thu Apr 5 23:26:58 EDT 2007


Hello all

I have a somewhat unusual question regarding my myth LVM volume.  
Tonight one of the disks in the LVM volume started returning errors.  
So I need to replace it. Luckily for me, I just happen to have a  
replacement disk on hand (that arrived today and was slated for other  
purposes, believe it or not... pure serendipity). Unluckily, the  
replacement is IDE, whereas the failing disk is SATA. As I write  
this, I am using dd_rescue to copy block-by-block from the failing  
disk onto the replacement IDE disk. This leaves me with a question of  
how I will slip the new disk (/dev/hdc) into the lvm  volume to  
replace the previous disk (/dev/sda) without lvm "having a cow".

As I mentioned, I'm using dd_rescue instead of the standard lvm  
management tools in order to minimize writes and possible further  
data loss on the failing SATA disk. So the standard lvm disk moving/ 
replacement instructions won't work for me. Also, once I take the  
sata disk out of the machine, the other two sata disks will shift  
device names. So I need to figure out where lvm keeps its device  
names and modify it. /dev/sda's lvm data will need to be read from / 
dev/hdc, /dev/sdb's lvm data will need to be read from /dev/sda, and / 
dev/sdc's lvm data will need to be read from /dev/sdb.

Are there any lvm users out there who can offer any suggestions?

Thanks

--

Kurt Yoder
http://yoderhome.com



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