[Discuss] lvm snapshot cloning

[markw at mohawksoft.com (markw at mohawksoft.com)]

I should discuss more what I want to do with LVM and maybe it makes more
sense.

First, the statement of problem.
Hard disks are big and fundamentally slow.

Suppose you have a 1TB hard disk. How on earth do you back that up? If you
use a 1TB USB hard disk (USB 2.0) At best case, you'll get about 30MB/s.
(You won't get that fast, but it is a good round number for discussion)

1TB is 1,099,511,627,776 bytes. At 30MB/s that's a little over 9 1/2 hours
to backup.

If you use a dedicated high speed SATA or SAS drive, you may get a
whopping 160MB/s. That's 1 hour 49 minutes.

Think now if you want to pipe that up to the cloud for off-site backup.

With snapshots, you can back up a consistent state, as if your 2 hour
backup happened instantaneously, but you are still writing a lot of data.

However, there is a better optimization here. The snapshot device "knows"
what is different. You don't have to really backup 1TB every time, you
only have to backup the changes to it since the last full backup.

I can't give too much away, but I think you get my drift. If the data only
changes 5% a day, and you can track that 5% a day. You can make an
effective backup of 1TB of data in 29 minutes to the USB drive.

Think about it.

LVM is more than capable of doing this.