[olug] LVM and RAID Was: To RAID or not to RAID

[Dan Linder]

Just to recap:
1. RAID 5 (and 6, probably others - see
http://en.wikipedia.org/wiki/Standard_RAID_levels) provide the ability to
make multiple drives appear as one big drive to an operating system, so
five 1TB drives look to be 4TB of usable storage.
2. LVM also allows for multiple drives to be used together and divvied into
partitions which can grow (and shrink).
3. EXT4 and other filesystems (which reside on top of the partition) can be
grown or shrunk depending on how much un-used space is available.

I'm familiar with ZFS in the Solaris world - it's a combination of all
three of those (keeping it simple), but due to the licensing that ZFS is
released under it can NOT be officially used in any Linux kernel or
distribution.  I'm sure there are places to find the Linux-compatible
sourcecode and driver, but I don't want to go there.

Is it possible to setup LVM with MDADM to setup a RAID at the hardware
level that doesn't have to be rebuilt when I purchase another HDD?

In the Linux world I believe "btrfs" provides this, but I've never used
it.  Does anyone have any use of it beyond "I played with it in a lab one
afternoon"?

Thanks,
Dan

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