Sorted Strings Table (SSTable) is the persistent file format used by Scylla and Apache Cassandra. SSTable is saved as a persistent, ordered, immutable set of files on disk.
Immutable means SSTables are never modified; they are created by a MemTable flush and are deleted by a compaction.
The location of Scylla SSTables is specified in scylla.yaml data_file_directories parameter (default location: /var/lib/scylla/data).
SSTable 3.0 (mc format) is more efficient and requires less disk space than the SSTable 2.x. SSTable version support is as follows:
SSTable Version |
Scylla Enterprise Version |
Scylla Open Source Version |
|---|---|---|
3.x (‘md’) |
2021.1 |
4.3 and above |
3.0 (‘mc’) |
2019.1, 2020.1 |
3.x, 4.1, 4.2 |
2.2 (‘la’) |
N/A |
2.3 |
2.1.8 (‘ka’) |
2018.1 |
2.2 |
In Scylla Enterprise 2021.1, Scylla 4.3 and above, md format is enabled by default.
In Scylla 3.1 and above, mc format is enabled by default.
For more information on each of the SSTable formats, see below: