An Investigation into Transport Protocols and Data Transport ...

A.2. Network Interface Cards 273
larger than 100MB, the optimal write file size is less than 400MB under
RAID-5. The decrease in RAID-0 write performance with file size is not
as pronounced, but all cards observe a stepped decrease in performance
with files larger than 1GB.
A major factor that should be considered in the feasibility of these tests
is that the test programs are only single threaded and only read and/or
write a single file at any one time. This type of access to files is unlikely
in real world scenarios - especially as RAID systems are often deployed on
busy server systems which are shared by many users accessing different files
at the same time. The result of this would be a marked decrease in the
performance achieved in ‘real-world’ environments. However, in-depth study
of user access patterns would be required to give a realistic representation of
expected multi-user performance.
However, the tests do serve to demonstrate the optimal performance
achievable by the various RAID systems tested and demonstrates that the
raw performance achievable under RAID-0 is capable of reading and writing
data in the order of a gigabit/sec. However, the requirement of fault
protection and data integrity is often more important than transfer speeds,
and as such it is very unlikely that RAID-0 systems would be deployed in
real-world environments. It was shown that this trade off for file integrity
and protection would result in a decrease in write performance of up-to 50%.
A.2 Network Interface Cards
The need for intercommunication between computer systems is often handled
using Network Interface Cards (NICs). These are defined by Layer 1 and