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Expansion Channel 1 from both controllers must be connected to the same ESM A of the first drive tray in the
drive tray stack. Expansion Channel 2 from both controllers must be connected to the same ESM B of the last
drive tray in the drive tray stack.
The expansion channels must not be connected together: Do not connect a cable between ESM A of a drive tray
to ESM B of another drive tray.
SAS channels are not tolerant of loops. Except for the ESM connected directly to the controllers, each ESM should
only have a single connection to the ESM before it and a single connection to the ESM that follows it (unless it is
the last ESM in the channel). Do not connect additional cables to ESMs to provide short-cut paths because this
step creates a loop in the topology.
The drive trays in the chain of connections from controller A are in the reverse order from those whose
connections start from controller B. That is, the last drive tray in the chain from controller A must be the first drive
tray in the chain from controller B.
NOTE It does not matter which of the two SAS In ports on an ESM you use for a connection, but it is best to follow
the conventions described in the documentation so your storage management software represents the storage array
consistently.
NOTE Some SAS ports might have a black plastic plug installed. Remove the plug before you attach a cable to the
port.
As you install each cable, attach labels to the cable with the following information:
The controller ID (for example, controller A)
The ESM ID (for example, ESM A)
The ESM connector (In or Out)
The drive tray ID
For example, if you are connecting controller A to the SAS In port on ESM A in drive tray 1, the label on the controller
end of the cable will have this information:
CtA-Dch1, Dm1-ESM_A (left), In – Controller End
The label on the drive tray end of the cable will have this information:
Dm1-ESM_A (left), In, CtrlA
If you are connecting an ESM (Out) port to an ESM (In) port, the label on the first drive tray will have this information:
Dm1-ESM_A (left), OUT, DM2 ESM_A (left)
1. Attach a cable between the SAS Expansion (Ch1) connector on controller A in the flash array and a SAS In
connector on ESM A in the first drive tray.
2. Attach a cable between the SAS Expansion (Ch 1) connector on controller B in the flash array and the second
SAS In connector on ESM A in the first drive tray.
3. Are you adding more drive trays?
Yes – Go to step 4.
No – Go to step 6.
4. Attach a cable between the SAS Expansion (Out) connector on ESM A of the previous drive tray that you cabled
and a SAS In connector on ESM A in the next drive tray.
5. Are you adding more drive trays?
46 - 215-08288_A0_EF550 Flash Array Installation Guide
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