Dell POWERVAULT MD1000 - Manual (Page 10)

A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00
PAGE 10 5/06/2005
Split Topology
In split mode, the enclosure is divided into two logical enclosures; with each host connection
accessing its own set of physical disks. The primary Enclosure Management Module (EMM)
(located on the left side of the enclosure when viewed from the rear), accesses physical disk slots
7 through 14. The secondary EMM accesses physical disk slots 0 through 6. To connect a server
to an enclosure in split mode, the In port of each EMM should be attached to a connector of a
PERC 5/E controller. The Out port of an EMM in split mode is disabled, since enclosure daisy-
chaining is not supported in this mode.
Split mode is useful in deployments where a single PowerVault MD1000 storage enclosure help
provide limited amounts of storage each for two different servers.
Note: In split mode, each host server can see its own physical disks (e.g. drive., physical disk 0 – 6
or 7 – 14) but not the other server’s physical disks.
Note: Split mode does not support daisy-chaining.
Note: A system with a single EMM set in split mode will function properly, but the server will only
be able to see the physical disks that are connected to the EMM.
Dual Hosts
Figure 3: Split mode configuration
Daisy-Chaining Multiple PowerVault MD1000 Storage Enclosures
In unified mode, up to three enclosures may be daisy-chained together from a single PERC 5/E
controller port. A maximum of six PowerVault MD1000 storage enclosures (3 enclosures per port)
may be connected to a single PERC 5/E controller. (Note: Although this is a supported
configuration, one should consider total solution availability before attaching this quantity of storage
to a single-controller solution.). When connecting multiple enclosures, the first enclosure is
connected to the PERC 5/E controller via the In port of the primary EMM. The second enclosure is
connected from the Out port of the primary EMM on the first enclosure to the In port of the primary
EMM on the second enclosure. The connection is made with a standard SAS cable. The third
enclosure is connected in the same manner as the second enclosure.