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Topology Example 2

In this larger implementation, we have six clients accessing a total of 7.28 TB of storage. The SAN’s bandwidth availability is roughly 320 to 400 MB/s. This SAN is connected to an outer network, shown in green. Notice that all trivial Ethernet components are routed to this outer network, and only the nodes of the SAN are on the metadata network. Further, we have a standby metadata controller available to take over MDC duties if the primary MDC fails. For directory services, we have three choices:

  • The primary MDC is the open directory master of the SAN, with the standby MDC as a replica.
  • The standby MDC is the open directory master of the SAN, with the primary MDC as the replica.
  • The directory has been moved to the outer network, thereby allowing the Xserve units to just be MDCs (recommended).


  • 2 × Xserve RAID 5.6 TB (populated with six 400 GB drive modules per controller; the seventh is a hot spare, not used in the storage calculation)
  • 512 MB cache per controller (1 GB total)

Fibre Channel Switch

  • 1 × Apple qualified Fibre Channel switch

Metadata Controllers

  • Xserve, Xserve G5, or Xserve G5 cluster node
  • 1 GB RAM per controller
  • Apple Fibre Channel PCI-X card
  • Mac OS X Server v10.3.6 or later
  • Apple Xsan software
  • PCI video card (optional)

Metadata Network

  • 1 × unmanaged gigabit Ethernet switch

Client Workstations

  • Power Macintosh G5 or Power Macintosh G4 Dual 800 or faster
  • Apple Fibre Channel PCI-X card
  • Apple Ethernet PCI-X card
  • Mac OS X v10.3.6 or later
  • Apple Xsan software

Outer Network

Mac OS X Server running Open Directory to provide directory services, or a system running a similar service such as Microsoft Active Directory.

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