[Discuss] Backing up LVM partitions using snapshots

[Richard Pieri]

On 12/16/2011 12:38 PM, Derek Martin wrote:
> These numbers are false though.  If you need to back up 300TB of data
> using tape, you need way, way more than 300TB of tape.

Even if you need three times as much tape capacity as disk capacity then 
it still costs an order of magnitude less to buy the tapes than it does 
to buy a new storage frame.


> tapes (3TB uncompressed) run about $110, a 3TB drive runs about $130.
> So how much are you /really/ saving by using tape?  My guess is, over
> time, even with the expensive EMC solution, the savings for tape are
> negative; substantially more so with cheaper disk solutions.

This is marketing again.  Your $130 cost for the 3TB disk ignores the 
cost of the chassis to house it and the cost of the power to run it. 
Even a "cheap" chassis is a 5 digit expense.  I recently got a quote for 
an 8u rack server with 50 bays and no disks, and that came out to $12K. 
  Populating it is another $7K, and then power for it is about $8/day or 
$3K/year.

I can expand tape capacity by that much for the same cost, with 
redundancy, and I can infinitely expand my tape capacity without buying 
more hardware to house and power it.  That cheap storage chassis is 
fixed at 150TB.  Expanding that requires buying another $20K worth of 
hardware, allocating space in the data center, and providing power to it 
at a cost of another $3K/year.

So yes, I really am saving money with tape even with redundant media.

-- 
Rich P.