[ac29]

Sorry if this is offtopic, but can anybody explain the value proposition of tarsnap to me? It seems like a nice service and all, but the pricing is an order of magnitude more expensive than S3. If you are storing a few GB, this might not matter ("over half of Tarsnap users spend under $1 per month on storing their backups"), but if you have that little data, why not just dump it on a free Dropbox/Gdrive/etc account?

For more data, why not just use one of the many compressed, deduplicated, encrypted, incremental backup systems (attic comes to mind, I'm sure there are others) then just sync to S3 at a tenth the cost?

[segf4ult]

Because tarsnap is cheap, incredibly well documented, open source, and run by an awesome guy. It's an all around win-win.

[stephenr]

Rsync.net is even cheaper, has no requirement for a custom client, and arguably are more dependable because they're not just reselling S3

Edit: not to mention they offer actual support not just "contact the author" email link as a last resort.

[dmix]

I personally just trust Colin's crypto skills more than anyone.

[stephenr]

So you're saying you trust a single developer to both write an encryption tool and run the servers it talks to more than the combined possibilities using existing open source tools to create backups by encrypting data locally and storing it remotely via ssh/sftp?

[dmix]

Yes, when it comes to crypto I'd put my in trust in highly talented people over trusting my own ability to glue together a collection of OSS tools anyday.

[stephenr]

You seem to have misunderstood me.

I didn't suggest you should write your own encryption tool. There are numerous open source tools for creating encrypted backups, some do deduplication first too.

If the tool doesn't happen to support remote storage, a simple rsync or scp fills that part.

Literally the only thing unique about this service is the use of the term picodollars and the single individual it's all reliant on.

[GhotiFish]

I contacted the author today. He responded to me in 30 seconds.

[stephenr]

Try in 18 hours. Can you call him when something fails?

I'm not saying he isn't responsive I'm saying depending on a one-man-band who is responsible for the client software, server software and the underlying storage system (ie he is the owner of the s3 account) seems like a huge risk.

[vacri]

I assume he still has to sleep, at least on some days. :)

[pquerna]

tarsnap is not open source:

"While the Tarsnap code itself has not been released under an open source license, some of the "reusable components" have been published separately under a BSD license"

http://www.tarsnap.com/oss.html

The source code for tarsnap is available to view, so you could audit/inspect it yourself, but it is not under an open source license.

[ac29]

But its not cheap, which was my point. 100GB of storage costs:

$300/year at tarsnap

$36/year at S3

[lucb1e]

Finally, numbers other than picodollars and gigabyte months and unpredictable deduplication. This convinces me I don't want to store 4TB there at a huge cost($12,000 if it's really $300 a year for 100GB) compared to buying two 4TB drives (~€250 per 3-4 years) and placing them at a friend's with free bandwidth.

Don't get me wrong: managed, off-site encrypted backups are very attractive, and I might be willing to pay a premium, especially for software from a trusted person, but not the cost price hundredfold.

[patmcc]

Tarsnap isn't intended to be used as one-time backup like that, and it's super expensive if used that way. It's very cheap when used to backup (almost) the same 4GB for 1000 days in a row, which is what a lot of people/businesses need for their backup solutions.

[lucb1e]

It's not one time, I'd be incrementally writing updates to the disks. With a raspberry pi or something, the power costs are near negligible.

[stephenr]

Rough estimate here:

If you upload 4tb in a year, that's 333.33gb/month

So for tarsnap that equals

- $1k/year in data transfer charges (4000gb * $0.25 transfer charge * 12 months)

- $83/month per month of data (333gb * $0.25 storage cost/month)

- $6.4k/year for the first year ($83 * 78 cumulative months in a year)

So $7.4k for 12 months resulting in 4tb

If usage stays the same each year will add $12k to the incremental yearly cost

[stephenr]

Add another $1k to that for data transfer (assuming you only upload that 4tb once)

[girvo]

That sort of backup is what AWS Glacier is for, is it not?

[lucb1e]

I guess, I haven't really looked at it yet. And I'd have to find my own software to encrypt it before uploading. Tarsnap's software is one of the major selling points, at least to me.

[stephenr]

I hate to think the cost if you had to restore that data from glacier though.

[tomjen3]

How much do you save after dedublication? Tar-snap could be a lot cheaper if you do frequent backups or you often change little in huge files.

[ac29]

Backup tools like attic (which I use) include automatic deduplication. There are surely minor differences in implementation, but tarsnap isnt the only implementation of deduplicating backup.

[scott_karana]

Tarsnap can have different write/read keys for each backup archive, so (unlike with Attic) you don't need to worry about a compromised host deleting its entire backup history.

Other than that, Attic is pretty excellent too.

[Spooky23]

It depends on the data you are backing up. For dedupe friendly data, the costs come down significantly.