Pattern - SMB Filestore

The SMB protocol, as supported in windows and implemented in Windows Server and Samba products, is a TCP-based protocol for mounting filestores and remote printers.

Features

• TCP protocol for connecting to remote filestores.
• Versions of the protocol for many versions of windows.
• Implementations built in to windows
• Some Linux support

Advantages

• Works well with Windows.
• Integrates with Windows NT authentication (a derivative of Kerberos)
• TCP-based protocols can work over long-haul links
• Endpoints can detect loss of the remote server (especially if clients set SO-KEEPALIVE when opening the sockets)
• Windows 2000 and later has support for offline filesystems, which can cache part of a filesystem when offline, resynchronising when online.
• Disks can be mounted per-user, by issuing NET USE commands.
• Some failover is possible.

Disadvantages

• The Windows Explorer GUI handless missing/slow SMB servers very badly; the whole GUI can lock up. It is not good at working with unreliable or long-haul servers.
• Failure handling is mostly built in to the OS; it is very hard to add application-level policy.
• Security of offline files may be weak, laptops need to encrypt this part of their disk.
• As Active Directory is an extension of Kerberos, it may not work with standard Kerberos clients and servers.
• As a logged in user needs to mount the disks, it is hard for machines to mount disks until a user is logged in.
• The SMB protocol is continually changing; Samba follows but there may be surprises.

SmartFrog support

It is trivial to implement a component that executes a NET USE command; this can mount a disk for that specific user.