# What backend is used in mnesia for on-disk or memory and disk tables? **URL:** \ **Category:** Questions / Help\ **Tags:** mnesia\ **Created:** [April 30, 2025, 8:05pm UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717 "2025-04-30T20:05:41Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![coder-001](https://erlangforums.com/letter_avatar_proxy/v4/letter/c/a698b9/32.png) [@coder-001](https://erlangforums.com/u/coder-001)\ **Post date:** [April 30, 2025, 8:05pm UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717/1 "2025-04-30T20:05:41Z")
I have read on the elixir forum that mnesia retired dets for disk storage due to its size limitation. And I just wanted to know what is being used now. Thank you 😃 ---
**Author:** ![LeonardB](https://erlangforums.com/user_avatar/erlangforums.com/leonardb/32/1856_2.png) [@LeonardB](https://erlangforums.com/u/LeonardB)\ **Post date:** [May 1, 2025, 12:54am UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717/2 "2025-05-01T00:54:04Z")
That’s incorrect afaik. There are alternative storage backends that can be used though. 2 immediately come to mind; rocksdb and leveldb [https://github.com/aeternity/mnesia\_rocksdb](https://github.com/aeternity/mnesia_rocksdb) [https://github.com/klarna/mnesia\_eleveldb](https://github.com/klarna/mnesia_eleveldb) I use the rocksdb backend in a number of projects, and it’s been solid. ---
**Author:** ![dgud](https://erlangforums.com/user_avatar/erlangforums.com/dgud/32/191_2.png) [@dgud](https://erlangforums.com/u/dgud)\ **Post date:** [May 1, 2025, 7:40am UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717/3 "2025-05-01T07:40:49Z")
dets is still used for ‘disk\_only’ tables. 2GB limitation disk\_log is used for disk\_copies (no size limitation on disk). ---
**Author:** ![coder-001](https://erlangforums.com/letter_avatar_proxy/v4/letter/c/a698b9/32.png) [@coder-001](https://erlangforums.com/u/coder-001)\ **Post date:** [May 1, 2025, 12:34pm UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717/4 "2025-05-01T12:34:19Z")
Thanks for the insight, do you mind sharing why dets is still used for disk\_only tables despite its limitation? even if one decides to use table fragmentation it is still limited to non local\_content tables ---
**Author:** ![dgud](https://erlangforums.com/user_avatar/erlangforums.com/dgud/32/191_2.png) [@dgud](https://erlangforums.com/u/dgud)\ **Post date:** [May 6, 2025, 8:24am UTC](https://erlangforums.com/t/what-backend-is-used-in-mnesia-for-on-disk-or-memory-and-disk-tables/4717/5 "2025-05-06T08:24:16Z")
There is no other disk library inside OTP that can provide the functionality. And not easy to write it either.