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Comment by jeffbee | Hacker News Reader

(2020) isn't quite enough to clue the reader in that GFS was extirpated at Google more than a decade ago. Historical trivia only.

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> (2020) isn't quite enough to clue the reader in that GFS was extirpated at Google more than a decade ago. Historical trivia only.

Do you have more info about that? I was just Googling and found this:

https://pdos.csail.mit.edu/6.824/papers/gfs-faq.txt

> Q: Does Google still use GFS?

> A: Rumor has it that GFS has been replaced by something called Colossus, with the same overall goals, but improvements in master performance and fault-tolerance. In addition, many applications within Google have switched to more database-like storage systems such as BigTable and Spanner. However, much of the GFS design lives on in HDFS, the storage system for the Hadoop open-source MapReduce.

> https://cloud.google.com/blog/products/storage-data-transfer...

There is almost nothing public about Colossus. Here's some marketing fluff, but it's clear that Colossus is the successor to GFS and they compare scale (CFS >> GFS). https://cloud.google.com/blog/products/storage-data-transfer...

Also this slide deck https://www.pdsw.org/pdsw-discs17/slides/PDSW-DISCS-Google-K...

> In addition, many applications within Google have switched to more database-like storage systems such as BigTable and Spanner.

And where do BigTable and Spanner store their data? ;)

Interestingly, Colossus was initially designed to be the next generation BigTable storage. It turned out that other teams had a similar problem, so it has become a more general file system.

Turns out that big table is also useful to implement the storage layer for big table itself. Luckily turtles can be stacked on top of each others

BigTable stores it's data in Colossus, but Colossus stores it's metadata in BigTable :)

And Colossus stores its metametametadata in Chubby :)

https://www.pdsw.org/pdsw-discs17/slides/PDSW-DISCS-Google-K...

At Google the project to migrate GFS to Colossus was called Moonshot. It was endorsed by Eric Schmidt and became a top-down mandate. This goes into details of the migration: https://sre.google/static/pdf/CaseStudiesInfrastructureChang... (scroll to Chapter 1)

Thanks. This stat from the section on Diskless is interesting:

On shared machines, spinning disk reliability decreased compute reliability; 25%–30% of production task deaths were attributable to disk failure.

If you do the math for GFS, there are some scaling limits that make it quite evident how long ago Google had to leave GFS :)

Colossus retains a lot of the ideas of GFS, so I wouldn't say that this paper is completely outdated. I would recommend the Tectonic paper from Facebook for a more modern distributed filesystem example:

https://www.usenix.org/conference/fast21/presentation/pan

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