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 3.1 and above, mc format is enabled by default.
In Scylla 3.0, mc format is disabled by default and can be enabled by adding the enable_sstables_mc_format parameter as ‘true’ in scylla.yaml file.
For example:
enable_sstables_mc_format: true
For more information on Scylla 3.x SSTable formats, see below: