InfiniBand is an interface; just like
Fibre Channel (FC) or
Ethernet. As an interface, InfiniBand
carries different protocols. For example, the
SCSI command set can run on InfiniBand but
the SCSI command set can also run on top of FC.
iSCSI-carries the SCSI command set on IP
(Ethernet). By comparison, SAS is an interface for attaching
disk drives to servers, storage arrays to servers and to attach
disk drives within storage arrays.
@30650 You can have a server with an InfiniBand host channel
adapter (HCA) that attaches to an InfiniBand disk array. That
InfiniBand connection can run SCSI, iSCSI or some other protocol.
In turn, this can be talking to an array that has SAS disk drives
attached to it. In a small environment, you might use SAS to attach
a local SAS drive in a 1U blade server. Alternately, you might have
SAS in a disk array coexisting with SATA drives. Otherwise, you
might have network storage with iSCSI to access a disk array with
SAS disk drives in it.
These technologies all work together in a complementary fashion
even though they are typically positioned against each other. For
example, you might hear an argument for InfiniBand vs. iSCSI the
same way that FC is normally positioned against iSCSI -- they are
apples and oranges. InfiniBand is an interface, so it should be
compared to FC or Ethernet. Then, compare your protocols, such as
iSCSI vs. "SCSI on FC" or "SCSI on InfiniBand." InfiniBand, SAS,
iSCSI are all very much complementary.
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