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IBM TotalStorage DS300 and DS400 Best Practices Guide
There are several schemes that can be used to delineate the starting points of
various messages. One of the easiest to implement is by using fixed interval
markers. A special marker frame with a 32-bit pointer to the next iSCSI PDU start
is used.
iSCSI synch and steering
An optional layer can be inserted between the iSCSI and TCP layers called
“synch and steering”. This layer retains the ending address for every delivered
iSCSI PDU. It includes the minimum header information as part of its
encapsulation process. The information is used to deliver PDU contents to a final
address and aid with recovery operations if TCP frames are lost during
transmission.
2.3 iSCSI SAN and Network Attached Storage (NAS)
In this section, we give a brief comparison of iSCSI SAN and Network Attached
Storage. Figure 2-4 illustrates a comparison between iSCSI, Fibre Channel, and
NAS.
Figure 2-4 SAN/NAS comparison
Block I/O converted
to
File I/O Protocols
FCP SAN
NAS
iSCSI SAN
Pooled
Storage
Pooled
Storage
Pooled
Storage
File I/O converted
to
Block I/O
Data Base
Application
Block I/O
Data Base
Application
Block I/O
Data Base
Application
Block I/O
FC Network
SCSI Protocols
IP Network
File Protocols
(CIFS, NFS...
)
IP Network
iSCSI Protocols
.
Summary of Contents for TotalStorage DS300
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