Controller Memory - IBM DS4800 User, Installation And Maintenance Manual

Ethernet ports
RS-232 serial port

Controller memory

Each RAID controller has up to 8 GB of data cache memory, for a total of up to 16
GB cache memory per DS4800. Each RAID controller also has a total of either 512
MB (for models 80A/H, 82A/H or 84A/H) or 1024MB (for models 88A/H) of Intel
Pentium Xeon processor memory. The processor memory stores the controller
firmware, while the data cache is a buffer used to temporarily store hard disk drive
data during data read and write operations. A Cache Active LED on the controller
turns on when the cache contains data that has not been written to hard disk
drives. The Cache Active LED turns off when the cache does not contain unwritten
data.
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IBM System Storage DS4800 Storage Subsystem: Installation, User's, and Maintenance Guide
If the auto-negotiation process fails, the controllers will consider the link to
be down until negotiation is again attempted at one of these points in time.
For a 4 Gbps controller, the supported host-channel link speeds are 1, 2,
and 4 Gbps.
The Ethernet connections provide for out-of-band management
configurations to a host. The Ethernet ports are used for an RJ-45
10BASE-T or 100BASE-T Ethernet connection to each controller. Use the
Ethernet connection to directly manage the DS4800.
Use one Ethernet port for daily management of the DS4800. Reserve the
other port for use by service personnel or for subsystem monitoring
hardware that may be available in the future.
The two Ethernet ports must be connected into networks with two separate
subnet masks. Otherwise, the following Recovery Guru error will be
generated:
Ethernet Configuration conflict. Both Ethernet ports for a given DS4800
controller have been assigned IP addresses from the same subnet.
You can also make out-of-band management connections to the DS4800
controllers using the default IP addresses. The default IP addresses for the
controller A Ethernet ports 1 and 2 are 192.168.128.101 and
192.168.129.101, respectively. The default IP addresses for the controller B
Ethernet ports 1 and 2 are 192.168.128.102 and 192.168.129.102,
respectively. The default subnet mask for all four Ethernet ports is
255.255.255.0.
The RS-232 serial connection provides a diagnostic port for use by service
personnel only to perform diagnostic operations on the RAID controllers.
Attention: Incorrect use of the serial port can result in loss of data access
and, in some cases, in loss of data. Do not make any connections to the
serial port unless you do so under the direct guidance of IBM support
personnel.
Note: The maximum baud rate is 115 200 bps. The default baud rate
setting from the factory is 38 400 bps.