[Info-vax] VMS QuickSpecs

[Stephen Hoffman]

On 2015-08-13 15:41:17 +0000, Dirk Munk said:

> The Quickspecs don't mention SCS (used to be called LAVC?) 
> specifically. For clarity, the ethernet part could be enhanced by 
> specifically mentioning SCS and IP.

That's nothing new.   The HP OpenVMS SPD doesn't mention SCS, either:

<http://h18000.www1.hp.com/info/SP4229/SP4229PF.PDF>

It's arguably below the level of what's covered in the SPD or QuckSpecs.

SCS is System Communications Services, it's the underpinnings of 
clustering.  Among other supported paths, clustering has operated via 
CI, NI (Network Interconnect; Ethernet) and DSSI as a communications 
interconnect, and operates via SCSI as a storage interconnect.

LAVc Local Area VAXcluster support introduced the VAXport Port Emulator 
driver (PEDRIVER), which allowed clustering over Ethernet.   "VAXport 
drivers: In a VAXcluster environment, device drivers that control the 
communication paths between local and remote ports. (Examples are 
PADRIVER for the CI, PEDRIVER for the LAN, and PIDRIVER for the DSSI.)"

> Fibrechannel clustering would be nice too, after all Fibrechannel is in 
> a way comparible with ethernet, and it can also be used for IP.

That likely won't happen.  There used to be — haven't looked recently — 
too much variation among the different FC HBA interfaces to make 
supporting that approach be reasonably efficient.

More recently, FCIP has become one of the typical  approaches for folks 
using FC — so you can tunnel FC over an IP network underneath, and 
since you have an IP network, then there's no need for IP over FC.   
(FCIP follows the same reasoning behind IPCI, too: consolidation onto 
IP infrastructure.)

Toss into this discussion the arrival of server boards with embedded 10 
GbE NICs, of the availability of 10 GbE and 40 Gbps NICs, or of the 
recently-approved 100 Gbps 100GBASE stuff, why bother with FC?  If 
you're truly going high-end here, then that's usually InfiniBand.

FWIW, SuperMicro is selling a PCIe board that does both 40 Gbps 
InfiniBand and 10 GbE, and also selling 1U server boxes with dual 40 
GbE NICs.
http://www.supermicro.com/manuals/other/datasheet-AOC-UIBQ-M2.pdf
http://www.supermicro.com/white_paper/white_paper_ultra_servers.pdf

ps: there's also the question of whether going replicated host-to-host 
starts to makes sense over server to shared storage controller, for 
some environments.  One HGST prototype recently showed 2.5 microsecond 
latency for server to remote server to remote NVMe SSD storage access 
across InfiniBand, after all.   For other "more traditional" 
configurations, use fast host-to-host for most stuff and use FC or 
10GbE, 40 GbE or 100 GbE (as it arrives) iSCSI as the I/O bus.

>  In fact it was used by IP before it was used by SCSI (for storage SANs).

Not on VMS it wasn't.    SCSI is also not usable for host-to-host 
connections on OpenVMS, either.

Now where VSI might go with any of this, we shall learn.   But it 
wouldn't surprise me to see little more than incremental new hardware 
support on OpenVMS I64 — comparatively little beyond getting Poulson 
and Kittson servers to boot — and dedicating most of the available 
engineering and hardware efforts to the x86-64 port and to the hardware 
and buses that are available in the target x86-64 environment.


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