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Testing Sync at Dropbox

dropbox.tech

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Re: Testing Sync at Dropbox

#3

hey all, author of the previous post ( https://news.ycombinator.com/item?id=22595782 ) here, and I'm happy to answer any questions about the system! I think the author isaac is here too.

What are some of the trickiest edge cases that you try to account for? I can only assume that this kind of system is enormously complicated, given the high expectations from users and the complexity of the underlying environments.

Re: Testing Sync at Dropbox

#5

hey all, author of the previous post ( https://news.ycombinator.com/item?id=22595782 ) here, and I'm happy to answer any questions about the system! I think the author isaac is here too.

No question, just wanted to say that these blog posts are fantastic! Thank you for writing them.

Re: Testing Sync at Dropbox

#6
> To cover this layer of our codebase, we also run Trinity in a “native” mode, targeting the platform’s actual filesystem. However, running against the native filesystem incurs a huge performance penalty (roughly 10x), which in turn means Trinity Native can’t test as many different seeds.

What platforms do you test in “native” mode? What hardware backs it?

Re: Testing Sync at Dropbox

#7
post #4

Interesting, I learned this technique of having a third, synchronization intermediary with offlineimap and this helpful blog post: http://blog.ezyang.com/2012/08/how-offlineimap-works/

Thanks for sharing. This is indeed a very helpful blog post

Re: Testing Sync at Dropbox

#8

hey all, author of the previous post ( https://news.ycombinator.com/item?id=22595782 ) here, and I'm happy to answer any questions about the system! I think the author isaac is here too.

How smart is the sync engine's "merge" system? Can it cleverly merge files, or if it sees a single file that has diverged, does it just create a conflict copy and let the user sort it out?

Like, if both Alice and Bob has changed somefile.txt, but Alice has added a few lines in the beginning, and Bob a few lines at the end (i.e. something that would "git merge" cleanly), will the sync engine merge that into one file?

I'm very curious about what thoughts you guys had on this issue, because I can see arguments for both sides.

Re: Testing Sync at Dropbox

#9
post #8

hey all, author of the previous post ( https://news.ycombinator.com/item?id=22595782 ) here, and I'm happy to answer any questions about the system! I think the author isaac is here too.

How smart is the sync engine's "merge" system? Can it cleverly merge files, or if it sees a single file that has diverged, does it just create a conflict copy and let the user sort it out? Like, if both Alice and Bob has changed somefile.txt, but Alice has added a few lines in the beginning, and Bob a few lines at the end (i.e. something that would "git merge" cleanly), will the sync engine merge that into one file?…

I don't think Dropbox does merge at all does it?

The file object model wouldn't work for merging Word documents and such

Re: Testing Sync at Dropbox

#10

hey all, author of the previous post ( https://news.ycombinator.com/item?id=22595782 ) here, and I'm happy to answer any questions about the system! I think the author isaac is here too.

Whenever I start Dropbox (boot my laptop) it takes ~30min of maxed out single-core work to "catch-up" since the "last-update". It's just really annoying as it makes my laptop quite loud.

Why is that? Google Drive doesn't seem to need to struggle that much.

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