[plug] to LVM2 or not to LVM2...

[Denis Brown]

Hello PLUG list members,

About to set up a new server with RHEL5 or Centos5

Default install uses LVM2 for the system disk.    For the data array 
however, which is a separate RAID5 array, I have a choice including whether 
to use LVM2 or not.

An attraction with LVM2 is the ability to re-size partitions painlessly and 
this can be important for a production database application which this 
is.   For example in the past I have opted for ext3 and manual 
partitioning.   After a while assumptions that seemed good at the time can 
turn out to be less than ideal and re-partitioning can be a pain.

The main question I have is "Where is the metadata stored, that defines a 
logical group and its logical volumes?"   On the system drive?   On the LVM 
itself?

Another way of looking at that is "What do I need to pay special attention 
to, in backing up, in order not to lose this valuable metadata?"

TNSTAAFL and this ability to shrink and grow logical volumes will have a 
small performance penalty.   I can live with that in favour of the 
potential flexibility.   But is this flexibility going to have a high price 
down the track?   Yes, data will be backed up, but it's best not lost in 
the first place :-)

Anyone with recent horror stories regarding LVM2?   It is not too late to 
change the specification to avoid the use of LVM.

Regards,
Denis