[CentOS] LVM question

Tue Jan 17 14:31:13 UTC 2012
Aslan Carlos <aslan at linuxadvanced.com>

On 01/17/2012 11:40 AM, Steve Thompson wrote:
> on LVM is quite safe as long as it is below 2GB

It's not possible put /boot on LVM when you working with GRUB.

Grub works with 2 stages:

1º - MBR ( Master Boot Record ) , with instruction to access the
partition where store kernel , initrd and grub.conf
2º - Reads the partition indicated on 1º stage (MBR), to read grub.conf
with all instruction to boot the OS.

Now the question why we cannot use /boot on LVM. LVM is a Logical Volume
Manager, GRUB no have support yet to read LVM. You'll see this LVM
structure after the kernel boot and load the LVM modules.

You could see what filesystems are support by Grub access your /boot
after installation, looking into /boot/grub.
 
Only Grub version 2 could access partitions /boot with LVM. ( I find
this information now )


-

You'll not have problem using SWAP on LVM, but we need think about all
situations.
If you running some software that use too much SWAP area, recommend you
put your SWAP on the firsts primary partition on your disk, because
there are area more fast I/O. If you want know more about that looking
for about ZCAV. (This is applicable to electrical mechanical disk, no
Solid State Disks,SSD).
Let's think you need more SWAP space, but your using SWAP on LVM, you
could create a new LVM and add to SWAP area.
swapon -s (you could see information how many swap partition or files
you have and how much is the use of them)



best regards,
--aslan