What powers Etsy

http://codeascraft.etsy.com/2012/08/31/what-hardware-powers-etsy-com/

by johnzimmerman • 14 years ago

166 44 14 years ago

codeascraft.etsy.com

druiid6• 14 years ago

It's very cool to see these kinds of posts. I always learn something from them and it's always neat to see what others have built to deal with a specific problem.

I wonder in this case why, if any specific reason Etsy is not utilizing virtualization of one kind or another? Basically they're building dumb-boxes that seem a much better fit to have a good number of slightly beefier VM systems and just rebuild bad instances from images (this would be especially good since they're already utilizing Chef).

I know that as an e-commerce firm this has helped us substantially to move toward this kind of a structure.

jcampbell1• 14 years ago

Several years ago, 37 signals wrote a post showing that moving away from virtualization improved response times.

http://37signals.com/svn/posts/1819-basecamp-now-with-more-v...

druiid6• 14 years ago

Well at least one thing to note there, is that post is from several years ago... both virtualization technologies have gotten better since then, as well as processors.

I think there are certainly specific web and db loads that aren't going to work as well under VM scenarios, but on the whole our experience has been positive. There will, I imagine, always be a slight 'slowdown' due to VM but with the gigantic push toward 'the cloud' right now, it seems to me one of the last things on the minds of most (and obviously Xen is highly used in that field, which is also what we use).

The bigger question I think is if you are using a highly CPU bound task which VM isn't always very good at. According to Etsy they are very CPU bound, so it makes some amount of sense.

runako2• 14 years ago

The OP says they can spin up a new bare metal machine in 10 minutes. It's likely the performance hit from running in a virtualized environment isn't worth shaving time off the 10 minute build.

druiid6• 14 years ago

I'd say there are other reasons behind using virtualization than simply quick system spin-up, such as easier/better integration with (Dev|Sys)Op tools, higher hardware->instance densities than you'll ever see from physical... etc.

I think the performance hit for many people is overstated. Unless you're at the long-tail of CPU bound instances I imagine it won't become very apparent. That said, if I'm missing something/incorrect then someone please correct me!

jgoulah• 14 years ago

FWIW we do use virtualization for our dev infrastructure (everyone gets a vm) which uses KVM/QEMU and our CI cluster which is LXC based

A bit about the dev infrastructure here: http://codeascraft.etsy.com/2012/03/13/making-it-virtually-e...

druiid6• 14 years ago

Thanks for the reply. Also interesting to see dev side... we run something similar although a bit more free-form with the internal developers, but that's being pushed into a more controlled environment ;).

I should also say it's a bit heartening to know of other e-com groups out there benefiting from an in-house stack rather than attempting to go 'TO THE CLOUD!'.

Dobbs• 14 years ago

Your point about rebuilding bad instances is just as easy to do with PXE and Chef/Puppet on bare metal.

avleenvig8• 14 years ago

sudo koan --replace-self sudo reboot -f

e12e2• 14 years ago

"Just as easy" might be an overstatement. Equally doable might be closer to the truth.

One example where virtualization is easier in practice is where you're not in control of the network intfrastructure -- ie: you subcontract management of switches etc to someone else.

For someone the size of Etsy that wouldn't matter much -- they have an obvious need to manage the entire stack. But for smaller institutions that might not target "scaling up to serve the entire public web" -- it is a factor.

Another example is if you have heterogeneous hardware -- it is much easier to just install a hypervisor that runs on every box and then manage that via your vm-toolset, that set up many different images. It also makes it easier if you need to run different os' -- do all your os images have drivers for all your hardware?

Granted, in theory OS' should abstract away hardware -- in practice, if you need to change out a few of your mysql instances running GNU/Linux to Microsoft SQL servers for a new project/change in workload -- being able to just spin down the old vms and up the new ones helps a lot in terms of agility.

But yes, it's absolutely possible to provision physical hardware as well.

lordlarm• 14 years ago

The Supermicro servers are really really great - one of the best investments I've done so far in 2012.

I bought mine (a Supermicro 2U Dual 3GHz Xeon 4GB 12 Bay Storage Server) for 400$ on eBay, with great service and terms. Recommended if you are ever in the need (or just want) a private server rack unit (1U, 2U or more).

druiid6• 14 years ago

I'm a big fan of Supermicro systems. They are probably one of the best bang-for-the-buck out there, although one has to purchase them with the understanding of the potential 'risk' of not having a giant support department behind them like Dell/HP. That's not a knock against Supermicro, just a note for the PHB type view.

caseyf• 14 years ago

Here's a new Supermicro form factor that I really like that wasn't mentioned in the post:

1U with 2 CPUs, 10 x 2.5" drive bays, redundant power

http://www.supermicro.com/products/system/1U/1027/SYS-1027R-...

mbell2• 14 years ago

I've had a few supermicro systems, some rack-mounted servers and a two 4U workstation pedestals.

I have one bad thing to say...they are loud, really _loud_.

Several years ago I had a 1U SM server in a rack full of HP servers I could hear the supermicro over all off them.

The 4U pedestal I have at home as a file server is the "super-quiet" model with 8 3.5" bays in front and it is still insanely loud. I had to to rig up a fan controller just to keep it livable to have in the apartment as the motherboard couldn't slow the fans down enough.

ChuckMcM• 14 years ago

https://plus.google.com/u/1/108703267897818623506/posts/GK2A...

One of the rows in our data center, lots of Supermicro goodness. We use the 12 bay 'jupiter' chassis for 2x SSD and 10X 2TB spinning rust per server.

mbell2• 14 years ago

I noticed something like this several times in the article: "Each machine has 2x 1gbit ethernet ports, in this case we’re only using one."

It sounds like a single switch failure could take down a large amount of their infrastructure. The seeming lack of geographic (or even datacenter) redundancy also seems a little dangerous at this scale.

avleenvig8• 14 years ago

There is detail about multi-site redundancy which we're saving for a future post :-)

You're right that a single switch failure would be impactful, but the impact of one switch going down would actually be very minimal. For example our web servers are spread out between many switches. The switches and network equipment have greater redundancy between them. - Avleen Vig, Staff Operations Engineer, Etsy

incision• 14 years ago

Yeah, that impresses me as a bit odd too.

I've seen situations where folks have done this because they believed they would need VSS/VPC or similar on the switch side, but ALB on the server should avoid that.

Perhaps they have a n array of access switches, each serving some subset to lessen the impact?

brooksbp• 14 years ago

VSS/VPC == MLAG... but what is ALB? I am guessing server uses one link until failure then uses the other? Even then, there are still network issues to overcome that may justify MLAG.

maglos• 14 years ago

In fact while testing mrsync to synchronize search indexes among prod servers they overloaded their switches cpu and took down the site for a few minutes.

donavanm3• 14 years ago

LAGs or redundant NICs is a mugs game. How deep do you go? Dual TORs up linked to dual aggs to dual transit routers, each with N+1 transit? all fed by A+B power infra, of course.

Or keep it simple. One nic for prod traffic, one for private/control plane. Separate TORs are nice, or just don't oversubscribe them. Keep critical data hot across racks. Plan for failure of any given host, then for dc failure. You'll have site power or transit failure waaay more often than a bad tor.

chrismealy2• 14 years ago

Anybody know what they use hadoop for?

mcfunley• 14 years ago

Analytics, search indexing, recommendations, various datasets that support search ranking, and some other things.

avleenvig8• 14 years ago

Tons of stuff! Stay tuned for that in a future post :-) We posted about this in 2010: http://codeascraft.etsy.com/2010/02/24/analyzing-etsys-data-...

Probably time for a refresh!

- Avleen Vig, Staff Operations Engineer, Etsy

chrismealy2• 14 years ago

Cool! Thanks.

lazyjones• 14 years ago

We use those 4-in-1 Supermicro systems too, but with AMD CPUs. They seemed a much better deal to us and have a few more DIMM slots (= 128MB per node in our ~2-3 years old boxes). The only issue was the almost-half-length PCIe slot, it's actually 6" instead of 6.6" so you have to be careful when buying PCIe cards (might not be an issue with the Intel version board layouts).

We've also invested in a 10gbe infrastructure rather early (we're smaller than etsy traffic-wise) and found it to be very useful for avoiding congestion issues when we need to transfer large files or pull data from a busy Postgres server.

As for HP servers, we avoid them since our DL360 D6 reported obscure fan failures when booting with an Intel 10gbe card and we had to buy the (slower) HP NetXen-based cards instead. Supermicro boxes are not that picky and you don't get the feeling that a vendor might be using dirty tricky to lock you in.

EliRivers• 14 years ago

It's powered by love of crafting stuff :p

avleenvig8• 14 years ago

If I could hand-craft circuit boards and CPUs, I probably would :-)

jonhendry• 14 years ago

And lots of Chinese mass production.

donavanm3• 14 years ago

"Nagios checks to let us know when the filesystem becomes un-writeable" Any specific reason you don't just panic? I've had RO fs edge cases bite me a few times.

"In the future we may even run fiber to these machines" Anything against 10g copper? Per port prices are getting crazy cheap.

"DNS servers, LDAP servers, and our Hadoop Namenodes ... need RAID for extra data safety" Anything you've had issues with? Host level redundancy with the first two has been pretty great IME, can't comment on name odes. The only issue I've run in to is poor LDAP clients not fast failing an unhealthy server when another is available.

avleenvig8• 14 years ago

RO filesystems can be bad, but usually they're soft failures for us: * Memcache can still work just fine * Db servers stop responding (and the app handles that fairly gracefully) * Web servers serve files from a RAM disk, so they keep working

No reason against 10G copper specifically - we haven't had to address the problem in detail yet. When we do, we might choose copper. Depends what happens when it happens :-)

We had a very nasty incident a few months ago, where the drive in one of the LDAP servers died. Well, it sort-of died. It started to time out a lot but didn't go fully offline. openldap kept running, but when you connected to it, the TCP connection would open and hang. This meant that all of our servers saw the server as "OK", but LDAP stopped working and caused all kinds of brilliant havoc :-)

donavanm3• 14 years ago

Interesting. I was thinking failure to persist updates, inconsistent health check results, those types of nasty corner cases.

Sure. Premature optimization and all.

Huh. SSD from a major chip vendor perhaps? I had one of those bite me just a few weeks ago. in my case it would have been fine if the drive offlined itself. but the intermittent io pauses killed performance, but not health checks. Actually, same type of problem RO FSs make me scared of.

What powers Etsy

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