I've built a REST API with a pretty decent latency. Each request is answered in ~100 ms with a thousand requests per second. This is however with a relatively low physical distance to the data center. The users of this API would, however, be spread all over the globe. From the US for example (to a data center in Germany), the response time for a single request is ~400 ms under no load.
What would be the best approach to deploying this API? I suspect multiple servers at different locations, with a load balancer in front. How would I ensure that the MySQL database would stay in sync between the servers in that case?
With multiple servers and a load balancer, the costs rise exponentially, which is something I can hopefully afford in the future, but not at the moment.
I'd love to hear your ideas!
Afaik. for big projects people use event sourcing with an event storage and microservices and message queues between them or a basic solution is polling the event storage through a simple REST API something like send me the latest events since the last event I received. If you can accept eventual consistency, then I think this approach can work pretty well. It makes writing somewhat slower, but reading can be very fast with it. No need to sync the MySQL databases directly, you just pull the latest events and use a projection to update the local MySQL database. So the event storage is the single source of truth.
I'm creating a RESTful backend API for eventual use by a phone app, and am toying with the idea of making some of the API read functions nothing more than static files, created and periodically updated by my server-side code, that the app will simply GET directly.
Is this a good idea?
My hope is to significantly reduce the CPU and memory load on the server by not requiring any code to run at all for many of the API calls. However, there could potentially be a huge number of these files (at least one per user of the phone app, which will be a public app listed in the app stores that I naturally hope will get lots of downloads) and I'm wondering if that alone will lead to latency issues I'm trying to avoid.
Here are more details:
It's an Apache server
The hardware is a hosting provider's VPS with about 1gb memory and 20gb free disk space
The average file size (in terms of content and not disk footprint) will probably be < 1kb
I imagine my server-side code might update a given user's data once a day or so at most.
The app will probably do GETs on these files just a few times a day. (There's no real-time interaction going on.)
I might password protect the directory the files will be in at the .htaccess level, though there's no personal or proprietary information in any of the files, so maybe I don't need to, but if I do, will that make a difference in terms of the main question of feasibility and performance?
Thanks for any help you can give me.
This is generally a good thing to do: anything that can be static rather than dynamic is a win for performance and cost (it's why we do caching!), but the main issue with with authorization (which you'll still need to do for each incoming request).
You might also want to consider using a cloud service for storage of the static data (e.g., Amazon S3 or Google Cloud Storage). There are neat ways to provide temporary authorized URLs that you can pass to users so that they can read the data for a short time and then must re-authorize to continue having access.
I don't have any experience regarding server hosting performance and how slow it gets so I wanted to ask this question.
My situation is, I want to host a ~1MB data file that needs to be downloaded by clients occasionally (once every 2-3 days). Of course I would like to minimize costs as long as it does not hurt user experience too much. I have data to indicate that I have clients globally.
I wanted to ask what the ballpark figure would be for the amount of time it would take to download a file of this size from other parts of the world (data is hosted in the US). Does anyone have any idea, for instance, how long it would take to download a 1MB file from locations such as Japan?
In case people are wondering, I personally would consider it OK if it takes under 10s to download in most parts of the world.
The first thing to do when you don't know how well something works... is to try it. Create buckets in all of the regions, store a file, and then download it and see.
The official AWS-centric answer for global content distribution is to connect a CloudFront distribution to an S3 bucket, and set things up so that your content is downloaded from S3 via CloudFront. This will tend to improve download speeds more when the user is distant from the bucket, even if the content isn't cached at a CloudFront edge, because most of the distance the download has to travel, it will be traveling on the AWS "Edge Network," a global network connecting CloudFront to the AWS regions, with fewer unknowns than the Internet at large between here and wherever.
I have a global client base, but -- for example -- my shopping pages' catalog images are stored in S3 in Oregon (us-west-2), but with links pointing to CloudFront.
Interestingly, the pricing for using both services together sometimes works out a little bit less expensive than using only S3. A possible explanation for this is that edge network egress traffic represents a lower cost to AWS and the rates are set accordingly. It's not a major difference, but once you understand the pricing tables, you'll see it.
1MB in 10s equals 800kbps. I'd be very surprised if any reputable hosting provider couldn't keep up with that speed of delivery. Looking at Akamai rankings (2015)*, in Japan (as in your example) the average user's speed is 15Mbps: your file would then be downloaded in 0.53 seconds.
( *Looking at the rankings, keep in mind that in countries where fast internet infra is yet to be ubiquitous, the "average speed" will be an average of fast corporate pipes and other premium links, with actual mainstream users having substantially slower speeds.)
Then in most cases, this will be up to the user's connection speed, and further, their ISP's international links, which can be much slower than their national or regional pipes. More so in countries with less developed internet infrastructure, where operators are cutting costs and corners.
In deciding if you need to deploy S3 or other CDN solutions, or no extra solutions at at all, you'll have to start with mapping up your user demographics. If there's a substantial sector from far-away countries with weak net infra, it makes sense. Otherwise, it doesn't seem likely that your target speed of 1MB/10s wouldn't be matched even without a special means of delivery.
If you have some but not substantial traffic from countries/regions where you reckon int'l traffic might be slower, and if you want to eliminate extra costs, I figure your users will survive even if it takes 15-20 seconds once in a blue moon as their speeds fluctuate. (This is opinion-based relative to how picky your users are!) In such a case, I'd only bother with a CDN if I wanted to improve speeds across the board, e.g. for all requests for static resources, not just a single file requested every couple of days. Would make a more substantial contribution towards the general user experience.
Are there known limitations of S3 scaling? Anyone ever had so many simultaneous reads or writes that a bucket started returning errors? I'm a bit more interested in writes than reads because S3 is likely to be optimized for reads.
Eric's comment sums it up already on a conceptual level, as addressed in the FAQ What happens if traffic from my application suddenly spikes? as well:
Amazon S3 was designed from the ground up to handle traffic for any
Internet application. [...] Amazon S3’s massive scale enables us to
spread load evenly, so that no individual application is affected by
traffic spikes.
Of course, you still need to account for possible issues and Tune [your] Application for Repeated SlowDown errors (see Amazon S3 Error Best Practices):
As with any distributed system, S3 has protection mechanisms which
detect intentional or unintentional resource over-consumption and
react accordingly. SlowDown errors can occur when a high request rate
triggers one of these mechanisms. Reducing your request rate will
decrease or eliminate errors of this type. Generally speaking, most
users will not experience these errors regularly; however, if you
would like more information or are experiencing high or unexpected
SlowDown errors, please post to our Amazon S3 developer forum
http://developer.amazonwebservices.com/connect/forum.jspa?forumID=24
or sign up for AWS Premium Support
http://aws.amazon.com/premiumsupport/. [emphasis mine]
While rare, these slow downs do happen of course - here is an AWS team response illustrating the issue (pretty dated though):
Amazon S3 will return this error when the request rate is high enough
that servicing the requests would cause degraded service for other
customers. This error is very rarely triggered. If you do receive
it, you should exponentially back off. If this error occurs, system
resources will be reactively rebalanced/allocated to better support a
higher request rate. As a result, the time period during which this
error would be thrown should be relatively short. [emphasis mine]
Your assumption about read vs. write optimization is confirmed there as well:
The threshold where this error is trigged varies and will depend, in
part, on the request type and pattern. In general, you'll be able to
achieve higher rps with gets vs. puts and with lots of gets for a
small number of keys vs. lots of gets for a large number of keys.
When geting or puting a large number of keys you'll be able to achieve
higher rps if the keys are in alphanumeric order vs. random/hashed
order.
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So, I have a dedicated server. I host about dozen or so small sites.
Is there a real benefit in using S3(or Mosso) for my image and static file hosting? My server has more than enough disk space, or am I completely missing the point of S3?
I keep reading about how wonderful and cheap it is, and I ask myself "self, why aren't you using this" and the reply is always "why?"
if you're running within the included storage and bandwidth of your server and your needs are being served well, you are already doing the simplest thing that is working for you and that is where you should always start. Off the top of my head I can think of a couple reasons why you may want to move some storage to S3 in the future:
Your storage or bandwidth needs grow beyond what you have and S3 is cheaper than upgrading your current solution
You move to a multiple-dedicated-server solution for failover/performance reasons and want to be able to store your assets in a single shared location
Your bandwidth needs are highly
variable (so you can avoid a monthly
fee when you're not getting traffic) [Thanks Jim, from the comments]
If you run an entire website off of a single machine, and that machine is more than enough to handle your site, then kudos, images are not a bottleneck that needs solving right now. Forget about S3 for now.
However, as your server gets busier, you will want your server to be spending all of its time doing server things. Transferring static content like flat HTML files and images is an easy, dumb job, and wasting precious active connections, bandwidth, and CPU cycles on them is no good. By switching to S3, your server can concentrate on doing what's important, which is whatever your program actually DOES.
S3 also has benefits of being distributed around and attached to what's probably a fatter pipe than your server, which means the images will show up slightly more quickly on your client's machines, so that's an added bonus.
S3 is also backed up, which means that it makes for a pretty nice place to store pretty much any private data under the sun, in addition to stuff that you want to serve to others (although don't confuse the permissions settings between those two things -- in fact, you may want to use separate accounts entirely).
S3 is also nigh-infinite, which means that if you want to let users upload files to your site (profile images, attachments, etc), S3 is a great choice so that you don't have to constantly worry if your server is going to run out of disk space (obligatory $$$ warning here).
But like I said at the top, if you're a one-server setup with a handful of users, none of this really matters. It's a tool like any other, and it may not be something you need yet.
It's simply a matter of doing the numbers: given a certain amount of traffic for a set of files, you can calculate exactly how much hosting those file on S3 would cost you, and you should be able to do the same for your current provider. If the number is lower for S3, there you have your reason.
An added benefit is that S3 scales pretty much linearly with traffic and you pay only for what you actually use, whereas most providers charge you a flat fee no matter how little traffic you actially have, and some will gouge you badly if you ever exceed the maximum traffic included in the flat fee.
Better speed and availability could be an additional benefit.
Basically, if you have a site that could potentially incur wildly disparate traffic, then using S3 for its images and other static files means that if you're hit by the Slashdot effect, the site has a much better chance of staying reachable, and you have a much better chance of avoiding nasty surprises concerning excess traffic fees.
The advantages of Amazon S3 are reliability, scalability, speed and cost. Here is some info on each.
Reliability: Amazon stores your data in multiple data centers. If there was a disaster and one data center was destroyed your content would continue to be served from the second data center. It’s very unlikely that data you upload to Amazon would ever be lost.
Scalability: If one of your web sites becomes popular and millions of people visit the site, your web server will not be able to handle the load. In comparison when you upload your files to Amazon they are stored in multiple locations. If the load on your content grows your files are automatically replicated to more servers so your files will always be available.
Speed: Amazon has a service called CloudFront that works in conjunction with Amazon S3. When you activate CloudFront on your S3 content your content is moved to edge locations. These are servers that make your content available for high speed transfer.
Cost: With Amazon S3 you only pay for what you use. If you have a few files that get little traffic you will only pay a few cents a month.
SprightlySoft has a blog post which gives even more reasons why Amazon S3 is great. Read it at http://sprightlysoft.com/blog/?p=8
If you're hosting a high-traffic site, the bandwidth cost (and latency issues) of hosting images yourself makes S3 and other services like Akami attractive. For a low-traffic site, it probably isn't an issue.
I'd say that there's no reason if your base hosting plan provides enough space/bandwidth. Where I think it's useful is when your file transfers become enough that you have to look at buying an add-on of storage/bandwidth from the provider -- in that case, S3 may be a viable alternative. But if I'm paying $X/month and not using all of the storage, there's no upside to it.
On the other hand, if your capacity planning calls for you to someday exceed the provider's limits, S3 may be a good solution from the start so you don't have files being served from multiple places.
I would second the mention of "redundancy" -- you can count on any content that's in S3 to be distributed to multiple data centers, and effectively been very much always accessible for anyone with functioning network connection.
Cost may be another factor: data transfer rates for S3 are quite competitive.
And speed is the last one: you can access data VERY fast from S3. But that's more of an issue for data other than browser-viewable images.
For small sites, S3 or Mosso may not be that reasonable for image hosting, but if you have any video files (.wmv, .flv, etc...) or large downloads (app distributions, etc..), I'd still put them on S3 or Mosso to save potential bandwidth spikes if for some odd reason, your content becomes wildly popular.
You write:
My server has more than enough disk space, or am I completely missing the point of S3?
You are not missing the point if what you have on you server is write-once read-less-than-once stuff, such as disaster-recovery backups (which you hope will be read-never), because transfer times will not matter. The point of S3 is delivery speed.
First, S3 distributes your content geographically. End users benefit from shorter paths.
Second, S3 can act as a BitTorrent seed, which not only conserves your bandwidth, it means your most popular content will be distributed faster because it can take advantage of the ad-hoc swarm. There are reports on the AWS Discussion Forums that S3 support of the BitTorrent protocol is "very, very spotty." I have not tested it myself.
Many of you won't have this problem, but if you (and your web server) are located in Australia (read: the 3rd world of the Internet), you run into the issue that S3 does not have geographically close locations, which means there will be a higher latency on your images and other static content. Scalable: yes. Fast: no.
From what I hear, besides low cost, the main advantage is the ease of backup from an EC2 setup.
Link..
http://groups.drupal.org/node/2383
Speed might be the only benefit. If your dedicated server is simply networked through your ISP (which may well throttle upstream speeds even if downstream speeds are high) then you might find that your sites are often slow to load. If so, then S3 or another dedicated server provider can help. Other than that, I can think of absolutely no reason why Amazon's service would be more appropriate for you - especially with simple, static sites.
It's not really directly related to your actual hosting of web sites, but it's certainly an important part of it, especially if the sites don't belong to you alone -- S3 is a great backup solution. There are tools such as duplicity that can automatically and efficiently back things up onto S3 for you, and it's extremely cheap for this purpose. I back up a fairly large amount of data for less than $1/month.
Besides the Fat Pipe and Local Delivery arguments for S3 there is also the manner of a single server does not function optimally when its functioning both as a db server and as a file server. If your running any sort of db I would suggest offloading all your static files to s3. The cost is trivial and you will see pretty big performance gains on page load.