back of the storage expansion enclosure. The Link Rate switch enables you to
select the data transfer rate between the ESMs and the drives to either 2 Gbps or 4
Gbps. The Link Rate switch is only read when the storage expansion enclosure is
powered up.
Notes:
1. Do not mix storage expansion enclosures with different Link Rate speed settings
in the same drive loop.
2. The EXP810 storage expansion enclosure drive channel operates at either 2 or
4 Gbps fibre channel interface speed. The EXP810 SATA E-DDM CRUs have
an ATA translator card that converts E-DDM 3 Gbps SATA drive interface
protocol to either 2 Gbps or 4 Gbps fibre channel interface protocol. It is
recommended that the EXP810 enclosure speed is set to 4 Gbps when these
SATA E-DDM CRUs are installed and connected to storage expansion
enclosures running at 4 Gbps speed. The Link Rate setting speed must be set
accordingly. See Table 37 for more information. The enclosure speed of the
DS4700 Express Storage Subsystem that the EXP810s are connected to must
also be set to 4 Gbps.
Do not mix 2 GB drives and 4 GB drives in the same storage expansion enclosure.
If drives of mixed speeds reside in the storage expansion enclosure, the data
transfer rate changes depending on the configuration. Table 37 shows the data
transfer rates for drives of different configurations.
Attention:
Do not change the Link Rate setting while the storage subsystem is
running. Changing the Link Rate setting while the storage subsystem is running
could cause drives to fail. You must power down the storage subsystem and
storage expansion enclosures before changing the Link Rate setting.
Table
37.
Data
transfer
rates
for
drive
modules
Link
Rate
Switch
Setting
Storage
Expansion
Enclosures
with
2
GB
Drives
Storage
Expansion
Enclosures
with
4
GB
Drives
Storage
Expansion
Enclosures
with
Mixed
Drives
2 Gbps
Drives function in 2
Gbps mode.
Drives work in 2 Gbps
mode.
All drives work in 2 Gbps
mode.
4 Gbps
Drives do not come
online.
Drives work in 4 Gbps
mode.
2 GB drives do not come
online.
4 GB drives work in 4 Gbps
mode.
Use the following procedure to check the current setting of the data transfer rate
and change it, if necessary.
Attention:
All devices on the loop must have the same data transfer rate, which
means that you must set the link rate on the storage expansion enclosure to the
same rate as the storage subsystem to which it is connected. Information about
supported DS4000 storage subsystems can be obtained from the certified System
Storage Interoperation Center, which can be found at the following Internet location:
www.ibm.com/systems/support/storage/config/ssic/index.jsp
1. Locate the Link Rate indicator LEDs. Figure 52 on page 103 shows the
location of the Link Rate indicator lights on the back of the storage expansion
enclosure.
102
IBM System Storage DS4000 EXP810 Storage Expansion Enclosure: Installation, User’s and Maintenance Guide
Summary of Contents for DS4000 EXP810
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