apache/cassandra · error · RuntimeException

Failed importing SSTables

Error message

Failed importing SSTables

What it means

When moving/copying imported SSTables into the live data directory fails, SSTableImporter.importNewSSTables logs the failure and throws RuntimeException 'Failed importing SSTables' with the cause, aborting that directory's import. The rename/move of the prepared SSTables into place did not succeed.

Source

Thrown at src/java/org/apache/cassandra/db/SSTableImporter.java:206

                    {
                        logger.error("[{}] Failed importing sstables in directory {}", importID, dir, t);
                        failedDirectories.add(dir);
                        if (options.copyData)
                        {
                            removeCopiedSSTables(movedSSTables);
                        }
                        else
                        {
                            moveSSTablesBack(movedSSTables);
                        }
                        movedSSTables.clear();
                        newSSTablesPerDirectory.clear();
                        break;
                    }
                    else
                    {
                        logger.error("[{}] Failed importing sstables from data directory - renamed SSTables are: {}", importID, movedSSTables, t);
                        throw new RuntimeException("Failed importing SSTables", t);
                    }
                }
            }
            newSSTables.addAll(newSSTablesPerDirectory);
        }

        if (newSSTables.isEmpty())
        {
            logger.info("[{}] No new SSTables were found for {}/{}", importID, cfs.getKeyspaceName(), cfs.getTableName());
            return failedDirectories;
        }

        logger.info("[{}] Loading new SSTables and building secondary indexes for {}/{}: {}", importID, cfs.getKeyspaceName(), cfs.getTableName(), newSSTables);
        if (logger.isTraceEnabled())
            logLeveling(importID, newSSTables);

        try (Refs<SSTableReader> refs = Refs.ref(newSSTables))
        {

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Free disk space on the target data directory and retry the import
2. Run the import so staging and the data directory share the same filesystem (rename must be same-device)
3. Remove stale/partial files from previous failed imports in both the import and data directories, then retry
4. Fix file ownership/permissions so the Cassandra user can write into the table's data directory

Example fix

// before: import dir on a different filesystem than data dir
nodetool import -- ks table /mnt/usb/import   # cross-device move fails
// after: stage on same filesystem as data
mkdir /var/lib/cassandra/data/import && cp /mnt/usb/import/* /var/lib/cassandra/data/import/
nodetool import -- ks table /var/lib/cassandra/data/import

// preflight before import
assertSameFilesystem(importDir, tableDataDir);
requireFreeSpace(tableDataDir, sizeOf(importDir) * 1.2);
requireWritableBy(tableDataDir, cassandraUser);

When it happens

Trigger: importNewSSTables moves verified, renamed SSTables from the staging/import directory to the table's data directory; an I/O error (disk full, permission denied, cross-device rename, existing target files) occurs and the directory is not a designated failed directory.

Common situations: Insufficient disk space on the target data volume; import directory on a different filesystem than the data directory; leftover files from a previous failed import with the same names; permission mismatch between the importer process and Cassandra's data dirs.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• Failed to import sstable <filename>
• FSReadError (wraps IOException reading TOC file)
• Exception occurred while writing to
• Corrupt flags value for clustering prefix (isStatic flag set
• Corrupted sstable. Invalid flags found deserializing Deletio

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/58964a3f62762b6f. Report an issue: GitHub.