Combining Unlimited and Local Storage Databases

It is possible to create unlimited and local storage databases in the same cluster. However, unlimited storage databases tend to aggressively reserve space for the blob cache and fill it up, which can contribute to “Out of Disk” (OOD) errors. If you want to reserve a certain amount of space for local databases on the same cluster, then you must cap the unlimited storage database blob cache size by setting the maximum_blob_cache_size_mb variable. Set it to a value that leaves enough space for your local databases and any other requirements.

The maximum_blob_cache_size_mb variable is configured by default on startup, using heuristics. Users are likely to run into issues with disks smaller than 40GB, hence SingleStore also traces a warning on startup in this case.

To accommodate local databases you should manually set the maximum_blob_cache_size_mb variable to the initial default value minus the value you need for the local databases. This must be set on every leaf node manually since the available disk size can vary on each node. You will need to set it in the memsql.cnf file to preserve the value across restarts.

Last modified: April 1, 2024

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