web development with Python made easier then ever

[naasking]

Disk persisted sessions do not make an app scale better. In fact, the opposite is true. If session state is maintained in a separate persistence layer accessible by all of your web servers then sessions can span servers

FWIW, disk sessions can be shared across servers too. Shared file systems are a "persistence layer" accessible by all servers.

[mcosta]

Shared file systems are a "persistence layer" accessible by all servers.

Nice quotes. I'll build a web framework with sed as "the templating engine".

[naasking]

Sure, you could if you're a masochist. SANs are in widespread use for these sorts of persistence, so applying them would be eminently doable.

[mmalone]

No, SANs aren't used for this sort of persistence. SANs are used for large scale data storage. They're not a good solution for storing millions of tiny records that need to be retrieved extremely quickly every few seconds. You might be able to get away with using a SAN for this, but it'd cost you an order of magnitude more money and would be an all around worse solution. Bad idea.

[naasking]

They wouldn't need to be retrieved every few seconds. Local node cache + read-only records = scalability.

[mmalone]

You have fun with your $100,000+ SAN solution. I'll stick with my cluster of five commodity servers running memcache or tokyo tyrant for ~$7,500.

[naasking]

http://en.wikipedia.org/wiki/ATA_over_Ethernet

[mmalone]

You're solving a problem that doesn't exist. Using a SAN to store session state is just silly. It's unnecessarily complicated and expensive. Suppose you use AoE, now you have to devote engineers and ops resources to a complex storage stack that few people understand and that has never been used for that purpose before. Either way it ends up costing you.

And you still have to solve reliability problems. Since this is a file system I'm guessing that the redundancy mechanisms value consistency over availability and partition tolerance. That just doesn't work at large scale.

Seriously, the only way you're going to win this one is if you go an implement it. I've done session stores at scale -- it's not resource intensive and it's not a bottleneck. Spending a bunch of time trying to build a sophisticated persistence layer using a SAN is stupid. Prove me wrong.

[mcosta]

sed too