Third-party SCSI data transfers

Don Tolmie det at lanl.gov
Tue Sep 13 10:21:06 PDT 1994


In his posting of 9/9/94, Lansing Sloan of Lawrence Livermore National
Laboratory proposed making extensions to SCSI to support networked storage
devices.  This is similar in nature to IPI over HIPPI.  After using IPI
over HIPPI at Los Alamos, we feel that a better solution would be to put
the storage protocol, e.g., IPI or SCSI, on top of TCP or IP, and make the
storage system a true network partner.  The advantages I see to using TCP
or IP include:

1. TCP and IP are ubiquitous, running in most machines and over all major
media today, including Ethernet, FDDI, Token Ring, ATM, HIPPI, and Fibre
Channel.  Hence, if the SCSI command set ran over TCP or IP, then you
immediately can use any of the above media.  It would expand SCSI usage
beyond directly attached channels.

2. You can intermix media through routers, bridges, and gateways.

3. You can easily co-exist with other networked devices and systems.

4. You can take advantage of the large volume of work already done by the
Internet community (IETF) for such things as Address Resolution Protocol
(ARP), Network Time Service, Distributed Name Service (DNS), Kerberos for
security, and SNMP and other management tools.  I.e., the full TCP suite of
protocols.

5. TCP and IP are not restricted to LANs, but cover wide area networks as
well.  This may or may not be important for SCSI.

6. TCP and IP are robust, providing checksums, retransmission, and usage
with out-of-order delivery.

7. The majority of the work has already been done, tested, enhanced, and
proven in practice.  Don't re-invent the wheel if you don't have to.

8. Network File System (NFS) runs on top of IP, and may be a good starting
place.

Comments?

+===========================================================+
! Don Tolmie                        Internet: det at lanl.gov  !
! Los Alamos National Laboratory    Phone: 505-667-5502     !
! CIC-5, MS-B255                      Fax: 505-665-7793     !
! Los Alamos, NM  87545                                     !
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