SMA and LLA servers can be used to create a database engine that runs without any disk storage space. Diskless server is useful in embedded systems that do not have hard disks, such as line cards in a network router or switch.
Diskless server can contain both disk-based tables (D-tables) and in-memory tables (M-tables). D-tables typically take less space than M-tables. Because a diskless server does not use any disk storage space, it maintains all D-tables in the database cache. The database cache size (IndexFile.CacheSize) has to be configured to contain the whole database.
There are two ways to run a diskless server: as a single server (alone) or as a replica in an advanced replication system. In both cases, you need to start the server by using the SSC API or SSC API for Java function calls.
SSC API
▪Use SSCStartSMADisklessServer to start a diskless SMA server.
▪Use SSCStartDisklessServer to start a diskless LLA server.
SSC API for Java
▪Use startDisklessServer to start a diskless LLA server.
Diskless server alone
If you run a diskless server alone, it has no way to read data when it starts and no way to write data when it shuts down. This means that each time the server starts, it starts without any previous data.
Since the server has no way to write data to disk, if the server is shut down abnormally (due to a power failure, for example), then any data in the server is lost and cannot be recovered. You can reduce the risk of data loss by using the HotStandby feature to create a “hot standby” machine that contains a copy of the data. For more information about the HotStandby capabilities, see solidDB® High Availability User Guide.
Diskless server as part of advanced replication systems
A diskless server may be a replica in an advanced replication system. In this situation, the replica can send data to the master server and download data from that master server. Thus, even though the replica has no disk storage or other permanent storage of its own, it can make some or all of its data persistent within the advanced replication system.