8.1Network Appliance
Network Appliance markets very specific NAS servers that they call “Filers”. Filers are single-purpose front-end “thin servers” used exclusively for storage access. NetApps employs a feature called the “SecureShare” cross-protocol Lock Manager. NetApps literature claims that SecureShare provides comprehensive multi-platform (heterogeneous) file locking capability.
NetApps servers are single-purpose file servers running a proprietary OS called Data Ontap. UNIX users and applications do not run on the system. Therefore, UNIX-Windows concurrent file access is not an issue, and NetApps literature ignores UNIX file sharing issues - probably for this reason. SecureShare does offer an interoperability mechanism for Windows and NFS clients. SecureShare can protect Windows clients with Mandatory Share Mode (open mode) locks from concurrent file access UNIX/NFS applications, even if they do not participate in the advisory locking protocol. However, if a UNIX/NFS application is not properly coded to lock files, then SecureShare cannot protect other UNIX/NFS processes from concurrent file access data corruption. If SecureShare allows data to be corrupted by UNIX/NFS concurrent file access, then providing Windows Share Mode (open mode) locking protection from those same UNIX/NFS processes has limited value11.
Based upon Network Appliance documentation, SecureShare provides the following file locking ability:
| Mandatory Share Mode (Open Mode) | | Network Appliance |
| | | | |
| Lock Windows | | Yes |
| | | | |
| Lock UNIX – no advisory locking | | Not Applicable |
| | | | |
| Lock UNIX – advisory locking | | Not Applicable |
| | | | |
| Lock UNIX/NFS – no advisory locking | | Yes11 |
| | | | |
| Lock UNIX/NFS – advisory locking | | Yes |
| | | | |
| Lock PC-NFS | | Yes |
| | | | |
| Byte Range Locking | | |
| | | | |
| Lock Windows | | Yes |
| | | | |
| Lock UNIX – no advisory locking | | Not Applicable |
| | | | |
| Lock UNIX – advisory locking | | Not Applicable |
| | | | |
| Lock UNIX/NFS – no advisory locking | | Yes11 |
| | | | |
| Lock UNIX/NFS – advisory locking | | Yes |
| | | | |
| Lock PC-NFS | | Yes |
| | | | |
| Oplocks | | |
| | | | |
| Break Oplock for Windows access | | Yes |
| | | | |
| Break Oplock for UNIX access – no | | Not Applicable |
| advisory | | |
| | | | |
| Break Oplock for UNIX access - advisory | | Not Applicable |
| | | | |
| Break Oplock for UNIX/NFS – no advisory | | Yes |
| | | | |
| Break Oplock for UNIX/NFS – advisory | | Yes |
| | | | |
| Break Oplock for PC-NFS | | Yes |
| | | | |
| 11 See Appendix B.5 | | |
