Dell VNX5800 VNX Series: Introduction to SMB 3.0 Support - Page 14

Directory Lease In SMB 2.0, Microsoft developed a directory content cache that resided on the client. This increased performance by reducing the amount of directory list requests transmitted over the network. However, a disadvantage of this feature is that when a client modifies files or folders, clients with a cached listing would not be aware of the changes even when the directory listing is refreshed by the user. SMB 3.0 improves the directory content cache with the concept of a directory lease. By setting a lease on a directory, the Windows client is automatically aware of a content change made in an open directory. If the content is created, modified, or deleted in the directory, the directory lease is broken. The next directory list request will be serviced by the CIFS server, instead of from the directory cache, with the latest changes. There are three types of leases: • Read-caching lease (R) enables a client to cache reads, and can be granted to multiple clients • Write-caching lease (W) enables a client to cache writes • A handle-caching lease (H) enables a client to cache open handles, and can be granted to multiple clients EMC VNX Series: Introduction to SMB 3.0 Support 14