Hacker News Reader

Comment by vageli | Hacker News Reader

> False equivalence. The engineer will be doing more than just cloud work.

> This comparison is the #1 flawed sales tactic the cloud companies use to convince you youre saving money

Time is of a limited quantity and time spent managing postgres backups (for example) is time not spent doing other (possibly more meaningful/impactful _to the business_) work.

View on HN

How much liability can you claim against AWS if there's an issue with their RDS backups?

How much liability can you claim against Cloud Employee if there's an issue with your RDS backups?

What is the chance that Amazon cause an issue with your RDS backup, versus a Cloud Employee?

The answer is definitely not clear to me at all

EDIT: no sarcasm, I legitimately don't know which I would choose as a biz owner

I would personally always have an off-platform backup to fall back on, as protection against the platform going down, accidental damage to data or malicious damage to data. Snapshots in cold storage too.

Liability? Probably none. See section "11. Limitations of Liability." here: https://aws.amazon.com/agreement/

RDS SLA's are here (doesn't mention backups though, so not sure how that's handled): https://aws.amazon.com/rds/sla/

Not a lawyer or anything, but my layman's understanding is that, you essentially are voluntarily opting-in to waiving liability when you sign up for AWS and accept the terms and conditions, and instead of liability, you agree to accept service credits if SLAs are not met.

what is involved in managing backups? isn't that just a cronjob?

First, you need to write the cronjob. But what goes in there? You need to decide exactly how you're going to make a backup, and the process may differ by what's being backed up. Ideally you want a quiescent snapshot, but the way you do that varies by application. What if the application is a distributed application, in which case you need to synchronize the snapshot process among all its nodes? What if it's a master-replica design, where the node that runs the cron job may vary based on the current topology?

And if you need some sort of cluster-aware lock to coordinate backups among different peers, you'll need to decide which system works for you, implement it, and maintain that as a separate system. And if that needs to be upgraded, figure out a bulletproof process for upgrading it while it's still being used as a coordinator.

Then, you need to ensure there's storage for the backup. You need to decide what kind of storage you're going to use, make sure you've got enough space, figure out how to encrypt the storage (very important in secure environments), how to protect the storage using authn/authz. And lots of environments have retention and storage lifecycle policies - you don't want to put the old backups on the expensive fast media; you want it on the cheap slow media. And some environments make you dispose of old data, so you have to figure out how to age it out but without ever losing the backups you want to keep.

Finally, you need to make sure the backups you create are valid and usable. So you'll want to build an automated regression testing procedure to ensure that every time you make a change (regardless of how minor) to the system being backed up or the backup process, that you end up with usable backups.

(Disclaimer: I work for AWS, but opinions expressed here are my own and not necessarily those of my employer.)

You make it sound like there aren’t cookbooks for many of these scenarios and that the company will have to invent these scripts and procedures by hand.

Yes it is work, but this company’s whole reason for being is to save AWS spend, so I assume they have patterns they employ for their clients regularly that achieve their SLO.

There are original-definition cookbooks and yet it still costs me time to provision my own lunch vs using the managed service of my corner restaurant.

Yes, managed services are better in many cases.

Sometimes there are cookbooks, but they are of varying quality and often don't have dedicated resources to maintain them, so I would use them with great caution. You also have to implement them and often maintain the underlying infrastructure.

But I was really responding to the brusque naiveté of the "just write a cronjob" response.

“managed services” don’t necessarily save you the headache of making sure backups are usable. But other points are valid.

There was a time when I used to think the same, then I found my backups were corrupted (or stopped because run out of space, etc) just in the moment when I needed them.

I once worked at an IT shop that worked closely with the construction industry. A new sports stadium was being built and we were doing panoramic photos during each stage of construction, and rendering them in a web app where the facilities team could “peel back the layers” and see what was behind the wall or under the floor all the way down to the foundation. This was... 15 years ago? So it was pretty neat technology and a little less ubiquitous than today.

Well, our storage server barfed and the data was gone. Went to restore from backups, all the hourly tar files were there... but were zero bytes.

We looked at the backup script the engineer had put together and it was one of those classic “didn’t give the right parameter to have tar recurse” type bugs. Unfortunately we lost all the photos of the foundation and much of the photos of the electric being run. Oops.

One wonders why tar even has an option (and a default!) to not recurse. What would be the use case for that?

The "normal" use case seems to have a recursive archival. Sounds like somebody chose the wrong default... would be an interesting software archaelogy project to figure out where this "feature" originated.

Not for a reliable solution. For example, assume you have a master and a replica database for reliability, what happens if the master, where the cron runs, fails? Do you remember to set up the cron up on the replica? From my experience, having worked on backup software, over 10% of servers that need to be backed up are not.

System reliability is hard, and the cloud makes that easier.

Need a lot of storage and make sure the backup is readable (view the files content or try a restore).

The number one backup solutions nowadays is AWS S3, because it's easy-to-use unlimited storage.

How does a company handle backups without S3? Usually they don't. That would require employees to buy machines/SAN with tens of TB of storage and maintain them (weeks in ordering and travelling to the datacenter once in a while). It's too much hassle so nevermind.

Easy to use unlimited storage is a sure recipe for not finding what you actually need, restoring the wrong backup, etc.

Unless you take your DR plans seriously, the cloud doesn't eliminate risk, it just changes it.

The place I work at forces a failover on a monthly basis, and does a full-on offsite DR exercise twice a year.

I'm sure it took time to set it all up, but now that it's there it takes almost no effort to continue.

The cloud eliminates the most common risks, that is ops + developers simply giving up on backups because there is nowhere to store them, and not being able to access them anyway.

Typical new sysadmin in large corp: The backup storage is full and backups have been failing since before I joined, should we do something about it?

Oh we raised tickets to request more disks. They will take months to arrive if they ever pass approvals.

Backups are a solved problem and has been for decades.

Can you think of a better example?

They’re a solved problem in the sense that the tools exist but that still has an ongoing operational cost to correctly setup, secure, monitor and test – and there are plenty of examples of expensive failures or security breaches caused by people thinking it was an easy solved problem.

Deciding whether you get enough benefit from doing that yourself is a classic business trade off which any experienced engineer should consider.

Reply on news.ycombinator.com