# Understanding the upper limit of 100TB databases

**URL:** <https://forums.foundationdb.org/t/understanding-the-upper-limit-of-100tb-databases/4148>\
**Category:** Using FoundationDB\
**Tags:** performance, operator\
**Created:** [September 15, 2023, 3:48pm UTC](https://forums.foundationdb.org/t/understanding-the-upper-limit-of-100tb-databases/4148 "2023-09-15T15:48:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hazz99](https://avatars.discourse-cdn.com/v4/letter/h/a5b964/32.png) [@hazz99](https://forums.foundationdb.org/u/hazz99)\
**Post date:** [September 15, 2023, 3:48pm UTC](https://forums.foundationdb.org/t/understanding-the-upper-limit-of-100tb-databases/4148/1 "2023-09-15T15:48:01Z")

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Hello!

I am exploring the use of FoundationDB as the storage layer for a large number of services in a multi-region deployment. I believe we have a similar problem space to Apple’s CloudKit, which uses many different FoundationDB clusters (from the QuiCK queuing system paper). How is this scale is achieved?

The documentation states:

> FoundationDB has been tested with databases up to 100 TB (total size of key-value pairs – required disk space will be significantly higher after replication and overhead).

I understand that [100 TB actually becomes ~500 TB](https://github.com/apple/foundationdb/issues/1363) (Github discussion) when replication/overhead is taken into account, but this feels like an incredibly small limit. I can buy a 100TB RAID array to put next to my desk.

The recommended solution from this [“Scalability performance benchmark”](https://forums.foundationdb.org/t/scalability-performance-benchmark/1261/2) forum post was to shard across multiple clusters. But doesn’t this break transaction guarantees?

I suspect I’m misunderstand something. Maybe there is a design pattern that addresses these problems. Can anyone explain this, or point me to relevant info?

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**Author:** ![hazz99](https://avatars.discourse-cdn.com/v4/letter/h/a5b964/32.png) [@hazz99](https://forums.foundationdb.org/u/hazz99)\
**Post date:** [September 15, 2023, 3:50pm UTC](https://forums.foundationdb.org/t/understanding-the-upper-limit-of-100tb-databases/4148/2 "2023-09-15T15:50:19Z")

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[Here is QuiCK paper](https://www.foundationdb.org/files/QuiCK.pdf) that I referenced. It seems to indicate the best practice is to scale out the number of clusters.