Storage

Single PVC (default)

By default, the operator creates one PVC per replica mounted at /var/opt/mssql. All SQL Server data, logs, and tempdb share this volume.

storage:
  size: 8Gi
  storageClassName: standard   # optional
  accessModes: [ReadWriteOnce] # optional (default)

Separate volumes

Set storage.volumes to create individual PVCs for data, log, and tempdb. Each volume gets its own storageClassName, accessModes, and size.

This is useful when:

• Data and logs need different storage classes (e.g. high-IOPS SSD for logs)
• You want independent capacity planning for each volume
• tempdb should use ephemeral storage since it's rebuilt on every restart

storage:
  volumes:
    data:
      storageClassName: fast-ssd
      resources:
        requests:
          storage: 50Gi
    log:
      storageClassName: fast-ssd
      resources:
        requests:
          storage: 20Gi
    tempdb:
      emptyDir:
        sizeLimit: 10Gi

Mount paths

Volume	Mount path	Purpose
mssql-data	/var/opt/mssql	MSSQL root + data files
mssql-log	/var/opt/mssql/log	Transaction log files
mssql-tempdb	/var/opt/mssql/tempdb	tempdb files

tempdb: PVC or emptyDir

tempdb is rebuilt from scratch on every SQL Server restart, so ephemeral storage is a valid choice. Set exactly one of persistentVolumeClaim or emptyDir:

emptyDir (recommended for most workloads):

tempdb:
  emptyDir:
    sizeLimit: 10Gi

PVC (when you need guaranteed IOPS or specific storage class):

tempdb:
  persistentVolumeClaim:
    storageClassName: ultra-fast
    resources:
      requests:
        storage: 10Gi

Immutability

storage.volumes is immutable after creation. Kubernetes does not allow changing VolumeClaimTemplates on an existing StatefulSet. To change the storage layout, delete and recreate the StatefulSet (data persists in PVCs).

mssql.conf

When separate volumes are enabled, the operator automatically configures SQL Server's file locations via mssql.conf:

[filelocation]
defaultdatadir = /var/opt/mssql/data
defaultlogdir = /var/opt/mssql/log
defaultdumpdir = /var/opt/mssql/data
errorlogfile = /var/opt/mssql/log/errorlog