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Lost an EBS snapshot on AWS once. The only way to provide some assurance in this space is to make sure your data is stored in more than one physically and commercially separate location.

This is the way. I get that not doing small-scale things yourself saves costs and that's why "cloud" exists, but if something is important to you or your organization, I cannot stress enough how useful having just a simple old data copy is. I've lost data to bad drives too often myself. Microsoft can erroneously close your paid-for account without recourse, or ransomware can try to extort you, but your data will simply not be lost if you have an offline (or more advanced: append-only) system with an hourly/daily/... backup on it.

There are various options here but the one I happened to have read up on (and then contributed documentation to make it easier to use safely) is Restic with Rest-server in append-only mode. It's not perfect (e.g. no compression yet, only dedup) but it's pretty good. If you're an individual or small–medium business, put your favorite raspberry pi equivalent in a closet and invest a hundred bucks in a hard drive big enough for the important documents, pictures of loved ones, etc.

A single drive shouldn't be your only backup, just don't put 100% of your trust in magic cloud. See also Atlassian this week: it may be down, but if you need to access the data of ticket xyz for a lead this week and you have a local data export, you can find the needed data.

you do get what you paid for

Not always. Pay for various games on Xbox, paid onedrive storage, pay for office licenses for the whole family, trip some false positive and still get your account banned with everything in it. You can talk to a wall or ask a judge to force Microsoft to give a reason, but then they can't actually show the reason because that's against some law in another country or something. It's fantastic. (Dutch, unfortunately) https://tweakers.net/nieuws/194930/microsoft-moet-blokkade-n... https://tweakers.net/reviews/9094/account-geblokkeerd-wat-nu...

That works until you find out the commercially separate location was using Amazon for their storage solution as well.

3-2-1 Backup: https://www.backblaze.com/blog/the-3-2-1-backup-strategy/

I would argue that EBS snapshots should not be used as a backup solution. EBS is reliable, but isn't engineered for the same durability as say, S3. These also become more unwieldy and less useful the older they get. Use EBS snapshots for rollback prior to making changes to your environment.

For durable backup I'd recommend storing objects in S3/Glacier. If you need to image an entire volume, make an AMI, which is stored in S3. Much more durable and targeted than a snapshot, and in the case of S3 objects, gives you benefits such as logging and version control.

Aren't EBS snapshots stored on S3? :)

They are (and in going to look that up I see that they're being pitched as more of a backup solution than they were previously) but given they're incremental and based on the existing EBS volume, I'd still recommend using something without dependencies.

I'm curious now as to how the EBS Snapshot was lost. If I had to guess, I suspect it had something to with that linkage back to the original volume. I maintain that the best backup has no dependencies on another resource existing.

We never got a straight answer from AWS.

We now run an instance in another region and account and rdiff-backup to it.

It's a good point. There is a relatively new feature to archive EBS snapshots [1] which stores non incremental snapshots

[1] https://aws.amazon.com/fr/blogs/aws/new-amazon-ebs-snapshots...

For most people Glacier is a terrible solution.

Why?

Folks, remember the 3-2-1 rule. IMO, it’s still extremely relevant, even in today’s cloud-centric world.

For data you can’t afford to loose, please, for the love of ${DEITY}, don’t store it with just one vendor. You never know what happens.

https://www.backblaze.com/blog/the-3-2-1-backup-strategy/

I think that people forget that you need two copies of your data under your control - and when your data is primarily on the cloud it is not data under your control; it is under the cloud company's control. You should have at least one copy that is physically in your possession, offline preferably, so that you have access to it.

For my cloud data, I sync it down to a local server and then sync that to removable offline media.

> For my cloud data, I sync it down to a local server and then sync that to removable offline media.

This seems like an excellent approach. Personally i use BackupPC which internally uses rsync and allows for incremental backups, compression and deduplication of said backups as needed, then copying the data over to additional HDDs with cron.

Works pretty decently on a slow residential connection, since it all happens in the background through WireGuard and one of my homelab boxes. Plus, BackupPC allows to test restoring backups with a single click, on a per-file or per-directory basis.

Of course, internally the solution is a bit of an Eldritch mess with Perl and whatnot, so other pieces of software like Bacula might be more popular in comparison.

You forgot to explain it:

Make 3 copies of your systems (just data if you can rebuild infra within your RTO)

Use 2 different media (compress then encrypt)

Move 1 copy off-site. (print the encryption key and store that in a fireproof safe)

Maybe not compress and encrypt depending on your thread model.

I generally think not encrypting data is a bad idea, but I can see a world where that’s a risk trade off you want to make (such as a hard drive with family photos). Why wouldn’t you want to compress it though?

Last time I surveyed my data, more than 99% of it was in an already compressed format (e.g. JPEG and HEVC), so compressing the backups added almost no benefit.

(Now, that’s not strictly true any more for JPEGs thanks to projects like lepton and JPEG XL which can indeed compress already-compressed JPEGs losslessly).

> Last time I surveyed my data, more than 99% of it was in an already compressed format (e.g. JPEG and HEVC), so compressing the backups added almost no benefit.

Personally, i use regular HDDs for storage of data (SSDs are out of my price point for anything but boot drives) and having fewer larger files seems to result in slightly better copying performance than having more smaller files. Though that might also have to do something with the file system and method of copying as well.

I agree, and I use tar to make backup volumes for this reason. I just don’t compress them.

Compression by itself:

1. Doesn't provide a meaningful size tradeoff for /family photos/

2. Doesn't provide a way to recover the data if it was damaged, at best you get a notification if a decompression routine failed the verification of uncompressed data

10 years ago I had a meaningful dedup ratio, nowhadays it is cheaper for me to have another 50Gbs than bother eith a dedup

There are cryptographic attacks that can exploit things being compressed. If an adversary can control some part of the files you compress together with sensitive information the size of the compressed backup provides a side channel into the content of the sensitive data.

I don't like 3-2-1. It's pretty fragile. I don't know how any sys admins can sleep over 1 remote backup.

My setup has 4-2-2 and using 2 different backup implementations for the remote, so bugs in them wouldn't be corrupting entire backups unknowingly at the same time.

Apparently the 1 local and 2 remotes are having generations of incremental backups as well.

That's not good but you do get what you pay for. Should never put all your eggs in one basket like that.

The €20 of credit made air accelerate out of my nostrils.

> The €20 of credit made air accelerate out of my nostrils.

Also they made sure you knew it's only valid for one year!

I came across tour of Hetzner datacenter[1] and it looks like a completely unprofessional setup, like castle on stilts. Does not inspire confidence.

[1] https://www.youtube.com/watch?v=5eo8nz_niiM

Could you tell us some of the red flags you see in this video? Considering it is a low cost hoster it looks fine to me, but I am not an expert.

If that's your standard for a garbage data centre... hmmm

Yeah I've seen way, way worse. Stuff like power cables zip tied to network cables and fibre lines. DUST. delerict hardware just sitting everywhere.

This is nice. What are you looking for, IBM dudes in white shirts running around?

looks pretty good

depends how localized the fire extinguishers are and how the power is distributed which is hard to see from the video

not sure what you expect, using 1-2U boxes or blades or something wont change the setup that much, it pretty much boils down to 'how many machines will die in the same time on power/fire' and how can we cool them as cheap as possible.

I just watched the whole thing and thought it looked really cool! Seems like a scrappy and self-reliant company that is focused on cost effectiveness and efficiency.

I've seen far worse. That said, the compute density is pretty low and the gear is rather older than what you would expect, they clearly are not optimizing for power efficiency but for capital efficiency, which means that as long as they can operate a box profitable they'd rather add more buildings than upgrade their servers. Interesting thermal arrangement, I wonder how well this would work in a fire, it looks like a giant chimney to me but maybe there is some secret sauce.

Hetzner has been traditionally renting dedicated servers for their customers - this might still be main part of their business.

This is also not their "state-of-the-art" DC. FSN is one of the older ones, I'd be interested in a tour of one of their Helsinki DC's which should be newer

FWIW if you focus on the modern areas, Google datacenters don't look much different.

That's why they're so cheap, compared to a lot of other offerings.

Looks like standard machines and not really servers, but there's nothing wrong there. Fairly clean wiring, no random cables, etc etc. HDD testing is a little sketchy, but they need to be quick-swapped, so it makes sense.

Ever been in a firewall/router manufacturers R&D/QA lab room? Those are so, so much worse. This is heaven by comparison.

Anybody have more color on the nature of the "recent, very unfortunate series of events in one of our clusters [such that] multiple disks failed in short succession"? What kind of "events"? A failed climate-control system? A berserk employee with a sledge hammer? Russian hackers? The Spanish Inquisition?

It seems odd that they'd be quite so vague and circumspect about it. Why not just say what it was, so we're not all left to speculate, perhaps for the worst?

A batch of disks in a RAID array that were all from the same manufacturing lot. Such setups have been known to have multiple drives fail within hours/days of each other. Best practice is to mix manufacturers or at least manufacturing lots when you build the storage array.

There's a couple of other well-known ways to screw up redundancy too, though I hope they're in far enough to know them.

One of my favorite is, if you want to store three copies of something on a lot of disks, randomly select which three disks you want to send the copies to so that each bit of content is stored on three random disks. It superficially seems very appealing; I have 3 copies of everything, nothing is likely to go wrong!

However, what you've actually created is a situation where if any three disks go down, you're guaranteed to lose data because as you scale up, the probability that those three disks were the three randomly-chosen disks for some set of data goes to 1. The probability of three disks going down at some point also likewise trends to 1 as you scale up.

Not saying that was the case here, just sharing it as one of the well-known pitfalls I find particularly interesting.

I keep hearing this pitfall, and then I keep seeing the results of idiots who don't understand that by not picking three totally at random, what they have created is a giant mess should any of those three fail, instead of a quick and easy to clean up mass that you are constantly raid rebuilding from.

How could any approach involving n copies of data mitigate against loss of n devices? What is the superior approach that avoids this pitfall?

If you store three copies of all your files, with copies uniformly distributed over the disks, and three disks fail simultaneously [1], you are guaranteed to lose data.

If instead, you break your disks into N/3 groups of three, and store each file three times in one group, you only lose data when all three disks in one group fail simultaneously. If you're lucky, you can lose 2/3rds of your disks before you lose data.

Edit to add:

If you're using mirroring, it's low cost to do mirroring by groups although uniform distribution can help with hotspots. With uniform distribution, even if one device has two popular files, the other copies of those files are likely to be on devices with only one popular file. With grouping, if one group gets two popular files, all devices in the group have two popular files and therefore elevated use.

If you're using a parity scheme (raid6/raidz2/some other erasure coding), the cost to do grouping is more apparent. Each group has the +X parity cost; If you did raidz2, and had 45 drives in a case, you could do one set of 45, and get 43 drives worth of storage, or three sets of 15 and get 39 drives worth of storage, or five sets of 9 to get 35 drives worth of storage, etc. In each of the smaller sets, you still can lose data with the first three failures, but you need an increasingly large number of failures to guarantee data loss. Also, the size of the data lost when there's a loss is smaller.

[1] or at least, the third disk fails before either of the first two failures is repaired

Intuitively, it feels as though grouping is a tradeoff that lowers the probability of a data loss event, at the expense of increasing the amount of data lost in a data loss event?

Edit: “proof” by example…

9 disks, replication factor of 3. 9 choose 3 = 84 ways to allocate a file’s replicas across the disks. If 3 disks fail, on average 1/84 of the total data is lost (assuming >>84 files).

Versus… 3 groups of 3 disks. If 3 disks fail, the probability of the second disk failure being in the same group as the first disk failure is 2/8, and then 1/7 that the third failure is also in the same group. (2/8)*(1/7)=1/28.

So a 100% chance of losing 1/84 of the data versus a 1/28 chance of losing 1/3 of the data. Same total expected amount of data lost.

You begin to see why this is a subtle problem, and why I think it catches so many people. Naive statistics, and perhaps "intuitive" statistics, say it's no different. In reality it's hugely different.

It is generally preferable in reality to take the second choice because additional realities intervene to give you time to deal with the problem, allowing the existence of fairly highly-reliable systems, whereas those same additional realities mean that in practice, you will lose data with some frequency if you select the uniformly random result.

Sometimes the better systems still catastrophically lose data, that is indeed inevitable as you point out, but what it takes to knock out that system would have result in lost data in the bad uniformly-random system, too, so in practice it's not much of a tradeoff.

I believe the more likely scenario was that they lost a disk and replaced it.. While the disk array was restriping, another disk in the raid array failed because of the restriping load, and all data would be lost at that point in a raid setup as they described.

I dunno, HPE had two issues with disks failing at specific power-on hours[1], and that wasn't the first time I've heard of similar things, just the one I can remember the vendor for. It's a lot more work to mix batches and stagger power on times than to build a bunch of disks systems at one time and turn them all on at once.

[1] https://www.hpe.com/us/en/services/sas-ssd-advisory.html

I used to have a couple of filers with thousands of disks on premise, we'd always have a dead disk somewhere. Keeping up with dead disks was almost a full time job, you'd open a case with the vendor, get them access to the datacenter, then be on the phone to guide them to the rack and verify that the new disk came online. To not go completely crazy, we usually batched these jobs once or twice per week. And even with double parity and replicated filers in two locations things can go wrong.

Also a favorite of mine is power cycling a machine. With enough disks, chances are high that a couple won't come back after they spin down.

A snapshot of the current data? So the data is still available and another snapshot can be created?

Also old snapshots

Snapshots are often used for deployment of systems. What happens if the snapshot you rely on as a base image gets lost?

Create a new one?

If the base snapshot is gone, all future snapshots that rely on that snapshot may be invalid. Depends on exactly how snapshots are implemented. Are they a delta of the previous snapshot? Are they a full copy of the device?

Hetzner snapshots are fully independent disk images, nothing more, nothing less.

Thanks! $20 seems kinda fair then, I guess.

Base images should be repeatable anyway using packer etc.

Even though this is a bit tricky on the hetzner cloud, because it requires the addition of a static route[1] to access the internet which isn't pushed by the DHCP, and I haven't been able to fully automate that in debians preseed for the life of me.

Yes it's offtopic, but that's one really frustrating thing. Maybe someone here has a solution.

1: https://docs.hetzner.com/cloud/servers/iso-installation-gate...

cloud-init?

cloud-init does help us, once we have a working linux, but we can also bake the static route into a base image.

The problem is that preseed is a very minimal linux environment and either relies on DHCP to work, or to use the usual network config DHCP sets (address, netmask, gateway). Arbitrary routes are not a possibility there. And ways to run abitrary commands to just <ip r> something come after the network initialization, which fails in that setup. The same holds for the kernel network bootstrapping parameters, I haven't found a way to add an arbitrary route there yet.

And for some reason, kickstart is able to handle this with it's centos/RHEL base.

It reads like it indeed does not affect live data in running cloudservers, yes.

Aside from backups, the snapshots can also be used as base images to provision new nodes though, losing those could indeed be inconvenient.

I was always under the impression that a snapshot should be an short-lived thing. E.g. you take a snapshot, make a backup or copy from that, then delete the snapshot. Where I work, the VM admins will only allow one snapshot at any point in time without special request and justification, and they encourage deleting the snapshot within 72 hours.

Depends on the solution, but in many systems snapshots are cheap, like zfs or btrfs. I can imagine ceph snapshots being quite cheap too.

Edit: people use snapshots to compliment backups too, you can do snapshots hourly and back a snapshot up daily. (They don't act as backups, more like "oops" revert solutions, humans are more likely to fail than machines)

If you're using VMware or Hyper-V the backups rely on a dirty "bitmap" of which blocks has been written since last backup so it only has to pull those from the system, this doesn't work with more snapshots for some reason. Enterprise backup solutions will just pull the entire machine and compare what's changed anyways, but you usually get a warning about it. So grumpy admins

Yes it's VMware.

You're using a rather narrow/implementation specific definition of snapshot.

I believe EBS snapshots are equivalent to you temp-snapshot, incremental/deduplicated backup/delete temp snapshot combination. Logically it's still a snapshot, because it contains all data of the volume at a specific point in time, but the cloud provider abstracts away the details of how it achieves durability.

> All snapshots you create are stored on our highly available storage systems.

Highly available right until they are not. Nice to see that your data is worth 20 bucks to Hetzner. I always liked them but this is a bit rude to put it mildly.

The storage system is highly available, but the data is not guaranteed to be :)

Availability and durability are different things.

S3 for example is designed for an availability such that it can fail 1 in every 10,000 requests on average and for a durability that can lose one object for every 100,000,000,000 objects you have each year on average.

NSS.

Better communication than Atlassian apparently.

It's really odd to see so many complaining when yesterday a thread about Atlassian was asking for precisely this type of communication.

They communicated what went wrong, how it happened (in a nutshell), apologized and stated how they're planning to do better.

They even threw in 20€ which when compared to the pricing of their snapshot storage is more than fair.

Shit happens, things go wrong. If you lost very important data because you only stored it in one location, then you're equally at fault. Especially when taking into account that they are a rather cheap service.

What more do you want?

Hetzner has been doing emergency maintenance on their backup drive systems (BX-XX) lately. Both of mine on separate accounts have had the notifications.

I've never trusted cloud provider snapshots because it's just paying more for something that might fail outside of your responsibility.

I have a local backup box and a remote one and they both sync stuff in from rsync on a cron job from multiple servers. Works great. In case of catastrophic failure (Which has happened a few times), putting my eggs in more than one basket has been extremely successful.

multiple drive failure... i wonder if they were all the same brand / model / batch

I remember being told years back with Digitalocean to not rely on their backups by one of the people that wrote their system. This made sense to me as they didn't even charge for it for the longest time. We do now use it some of the time and haven't had problems but there's always a second place we send images to (usually S3) as well as longer term offline archives.

Even when you consider that you might lose some data in an unlikely event, there still is value proposition in this kind of services. Easy restore compared to external services.

I wonder if this is related to the emails I've been getting since the start of March regarding maintenance on Storage Box Hosts? There were urgent maintenance ones on the 11th April as well.

The day I ordered my first Hetzner storage box (May 16) was the day I had my first Urgent Maintenance notice. Today the second one. "Urgent maintenance on Storage Box hosts XXX to XXX"

Never had any trouble with their vps offerings, but I'm not liking it.

There is no reason to rely on "triple replication" for data integrity. This has long been a solved problem. An appropriate erasure encoding can reduce the probability of loss ~ten-fold while consuming physically less space (i.e. 2x worth of replication). Companies forego this technology because they feel confident in their operational ability to address failures quickly and competently. That's what we're relying on for data integrity, not the math.

This email doesn't detail the integrity scheme, only that data was protected if no more than two disks failed, and more than two disks failed.

That could be three copies at 3x the storage cost, or it could be a RAID6 or raidz2 style system where the storage cost is essentially two disks out of the storage set size (which we don't know).

You could certainly increase the required failure count by increasing the parity, but if the problem was something like all the disks in the storage system hit the same fatal disk firmware bug at the same time (as speculated elsewhere in the thread, and is unfortunately plausible), then that doesn't really help much.

Erasure codes with lots of redundant drives is how online.net's C14 storage product works, but it is much more hassle than ordinary replication, since retrieval requires reading data from a lot of different drives to reassemble the shares, and similarly for splitting storage requests into shares and recording them. C14 is a Glacier-like product where you request a retrieval and your data is restore as an S3 object sometime (up to hours) later. That makes it easier, I expect.

I agree that this would be good as a last-ditch backup for stuff like Hetzner cloud snapshots, but the primary storage for those snapshots probably has to be ordinary RAID.

Fwiw I have a bunch of data in Hetzner Storagebox and have gotten several notices in the past few months that Storagebox would be temporarily offline for maintenance, which I assume meant raid rebuilds and/or drive swaps. The most recent of these was an "urgent" maintenance with less notice time than usual. It hasn't caused me any inconvenience, but I wonder if they have suffered a spate of drive failures recently.

Wow, twenty whole euro for blowing away your data. Let's hope Hetzner doesn't go bankrupt offering this immensely generous offer.

What would you like them to do?

Refund the total cost for a month at least?

Which would be less than the 20€ they've offered?

Just checked and for the location where I have my vm the price is:

> Snapshots cost €0.0125/GB/month (incl. 25 % VAT)

so €20 would cover a month for about 1.6TB of snapshots. Sounds pretty reasonable to me. But I guess it depends on how much data OP lost.

They refunded much more than that...

my monthly hertzner cost is 4.5 eur (and yes this includes snapshots).

For simple websites/blogs etc. you don't need much.

I host 12 different sites on this setup. And I could put up more.

I get around 0.5-1m views combined per month. They are mostly from one time zone, so traffic is not that spread out.

That's without cloudflare in front. I used to have it, but a lot of people said they are getting captched to death.

People* caught up in AWS bubble often don't realize how expensive it is. However I do use AWS at work extensively - right product for right occasion.

* Not saying that's true for you. But I notice that a lot of people I work with are surprised, when they learn this.

Not sure what OP is paying but I'm paying like €3 to Hetzner so it could be a sum that is comparative to the payment.

Hetzner Cloud – Data loss incident