Re: [PLUG] Two-Drive Software Raid 5?

[Rich Freeman <r-plug@thefreemanclan.net>]

On Tue, Jan 4, 2011 at 8:37 AM, Doug Stewart <zamoose@gmail.com> wrote:
> Why not create a RAID1 device with LVM over top, if redundancy AND expandability are your goals?

So, I'll probably put LVM over top regardless of how I implement the RAID.

However, I can't expand a RAID1 with LVM as easily as you might be
thinking.  Consider, with a two-drive raid5 I can add a 3rd 1TB drive
and get 2TB of redundant storage.  If I have a two-drive raid1 then I
can't add only a single 1TB drive without converting the array to
raid5.  I could add the bare drive to LVM and get the 1TB of space,
but I couldn't keep redundancy that way.

RAID5 expands much more efficiently than raid1.

On the other hand, maybe by the time I'd add more drives I'll be
buying a pair of 10TB drives and moving the data to btrfs anyway.  It
isn't like I've been adding 120GB drives to the array steadily all
along...
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