TrueNAS File and Storage Servers: SMB, NFS, iSCSI and ACLs

File access combines users/groups, permission bits, ACLs and security policies. Running an application as root can hide permission problems; prefer a justified, restricted service identity in production. Directory traversal permission differs from file-read permission. Sharing permissions do not necessarily override filesystem restrictions. Identify the actual runtime user, directory chain and ACLs when troubleshooting. Test narrowly required access rather than opening permissions globally.

Authentication proves who a user or workload is; authorization determines what that identity may do. Successful sign-in does not grant access to every resource. User sessions, service identities, API tokens and device certificates have different lifecycles. Design session duration, token renewal, employee departure, lost-device handling and emergency access alongside initial sign-in. Measure which existing sessions remain usable and which new accesses are denied when the identity provider becomes unavailable.

A trust boundary separates components governed by different access decisions; a failure domain groups resources that one event can affect together. Two VLANs do not create a strong trust boundary when routing between them is unrestricted. Backups in different folders still share a failure domain if one administrator can delete both. Assess physical location, identity provider, management account, network path and power source separately. Test which access paths and recovery options remain available when a component is lost.

Concurrent operations use locks or versioning to preserve integrity. Long transactions can block others; a deadlock forms a cycle of mutual waits. The database may terminate one participant, requiring safe application retries. Examine blocked and blocking queries together. Arbitrarily reducing isolation can change consistency guarantees. Test shorter transactions, consistent access order and suitable indexes under the same workload.

An application directory, mount point, logical volume and physical device belong to different layers. Inode exhaustion, read-only mounts and filesystem errors can stop writes even when space appears available. A snapshot often shares the same storage failure domain and is not an independent backup. Mount options and expansion methods depend on the filesystem. Verify mounts after reboot: writing to an unmounted directory can fill the wrong device.

A copy that boots does not prove application-data consistency. Operating-system caches, database logs and write ordering across disks or services affect the result. A crash-consistent copy resembles recovery after an unexpected shutdown; an application-consistent copy follows supported application preparation and write coordination. Validate transaction integrity, relationships between records and application behaviour after recovery, rather than only counting files. Confirm backup integration, application version and reported errors before assuming that consistency was achieved.