Iscsi San And Network Attached Storage (Nas) - IBM TotalStorage DS300 Best Practices Manual

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.
FCP SAN
Data Base
Application
Block I/O
FC Network
SCSI Protocols
Storage
Figure 2-4 SAN/NAS comparison
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IBM TotalStorage DS300 and DS400 Best Practices Guide
Block I/O converted
File I/O Protocols
File I/O converted
Pooled
.
NAS
Data Base
Application
Block I/O
to
IP Network
File Protocols
(CIFS, NFS...
)
to
Block I/O
Pooled
Storage
iSCSI SAN
Data Base
Application
Block I/O
IP Network
iSCSI Protocols
Pooled
Storage