This section describes the connection of storage systems for the various server types.
Properties of the type FC channel
Data transfer is serial via a fiber-optic cable.
The essential features of the type FC channel are:
full-duplex operation
a maximum of eight I/O operations (of different control units) can be executed simultaneously
connection of FC devices possible via FC switch (HNC and SKP can also be connected directly
maximum distance of an FC switch: 550 m
distances of up to 100 km are bridged without any major performance losses
only disks with FBA formatting are supported.
The following storage systems and devices are supported via the type FC channel:
ETERNUS DX and AF
ETERNUS CS8000
MTC devices LTO-x in the Scalar MTC archive systems
High-Speed Net Connect HNC
Service/console processor SKP
Figure 4: Type FC channel
Storage connection to /390-servers
SE-servers with SU /390 are connected to the storage via a FC-Switch and 16 Gbit/s or 64 Gbit/s channels.
Storage connection to x86-servers
There are different ways to connect x86-servers to storage:
local SAS-connection:
SAS-connection of the internal system-volumes (not approved for use with BS2000) and/or a rack-mounted storage-system ETERNUS JX.Fibre Channel (FC-peripherals, e.g. ETERNUS DX/AF)
Ethernet (Net-Storage)
All inputs/outputs to any peripherals are routed via the I/O-processors (X2000). The I/O-processor performance is very good and more than sufficient even for x86-servers under extreme loads.
The corresponding interfaces are managed within the X2000. The peripherals are connected via PCIe-Controllers.
SAS-connection
Direct Attached Storage (DAS) like the ETERNUS JX-series and its fast SAS-connection extends the storage-capacity of x86-servers.
When making use of the optional SAS-RAID connection with Backup Battery Unit (BBU) of the ETERNUS-JX system, the write-cache is going through a BBU relearn Cycle every 30 days. The BBU relearn cycle can take up to 15 hours and fully charges and discharges the BBU several times. During this time the write-cache is unavailable and without effect. For some workloads this can lead to extended run and response times. The BBU relearn cycle can be configured individually to for example only run during weekends.
FC-connection
X86-servers can use FC PCIe-Controllers with connection speeds of up to 64 Gbit/s.