Re: Glacier Storage

[Colin Percival <cperciva@tarsnap.com>]

Hi Hugo & list,

On 02/22/15 14:51, Hugo Osvaldo Barrera wrote:
> On 2015-02-22 11:56, Colin Percival wrote:
>> I discuss this in some detail in the blog post which Marcin linked to,
>> but the short answer is: It's not possible to mark particular files for
>> "cold storage" due to tarsnap's deduplication; it would theoretically
>> be possible to mark all the files stored with a particular key as being
>> frozen (glaciated?); but the implementation would be a pain given the
>> way that the tarsnap server works right now.
>> 
>> This is something I want to support eventually, but it's a long way
>> off.
> 
> Thanks for sending out an official response to this. I'd not crossed the
> above mentioned blog post before my initial email to this list.
> 
> Yes, I understand that freezing a single file is extremely inconvenient
> and would make duplication a pain/expensive.

It's not just that -- the tarsnap server doesn't know which blocks were reused
in an archive, so if "cold" and "warm" data was deduplicated together, you
could find that restoring a "warm" archive needed to read a "cold" block of
data.

> What I had is mind is something like "Backup up 200G of photos that I
> have in my home NAS. I'll only want these if my NAS blows up, which will
> hopefully be never."

Understood.  And for this, the best solution is probably to use something
other than Tarsnap.  Given that you're going to upload them once and never
touch them again (hopefully) there are lots of tools which will do the job
for you -- removing the need for deduplication makes everything much simpler.

> For the rest of my stuff and files I might want access to, tarsnap works
> fine for me.

Good!  And just to reinforce what I say very often: Tarsnap is *a* solution,
and it is the best solution *some* of the time, but most people will want to
use Tarsnap to back up only the most sensitive and/or "value dense" (cost of
losing data divided by the size of the data) material.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid