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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI: Flow ControlOK, I can buy that Peer to Peer Session stuff. So we, at least we seem to be in agreement on these items. (The length of "normal" Sessions, the length of Peer to Peer Sessions, and the Dynamic Buffering requirements for Storage Controllers.) So let me push this slightly. I also believe that when Storage Controllers are sold as iSCSI Internet (by that I mean long distance connect) capable, there will be a RAM Storage Feature that is recommended by the Vendor. Any one that just wants to use the Storage Controller in areas where SCSI Buss or FC distances apply today, might not need the additional RAM feature. I think that is the way this stuff will be sold (and need to be sold) and vendors will then compete on their more optimum ways of using the RAM buffers. There may be a variant of the above where the Vendor Sells the RAM Storage Feature based on the number of Concurrent Sessions the customers wants to sustain. And of course there will be combinations of RAM Storage Features for number of Sessions and Distance. Vendors will compete on how simple (in relationship to Cost and performance) their approach is viewed relative to the Distance and number of Sessions needed. If others believe this, then the stuff we have been talking about with regards to Flow Control is Mute and can be left up to TCP/IP and the various vendors implementations of the iSCSI/SCSI buffering algorithms. . . . John L. Hufferd Michael Krause <krause@cup.hp.com>@ece.cmu.edu on 10/04/2000 01:44:25 PM Sent by: owner-ips@ece.cmu.edu To: IPS@ece.cmu.edu cc: Subject: RE: iSCSI: Flow Control At 12:34 PM 10/4/00 -0700, John Hufferd/San Jose/IBM wrote: >Michael Krause, >First, a session usually lasts from Boot Time till it is Booted again or >stopped. The variant to this is a Storage Device being used in a manor >like a Mount or Map done with NAS. Even then, most folks, have that setup >so the Mounting and Mapping is done at bring up, though it is sometimes >done at other times, but even then it is left around. So I think the thing >you can say about Session Time as the term is used in the iSCSI context is >that it is LONG. > >I do not think we have consensus about the notification of available >buffers. With the way many systems work, is (as stated above), all devices >are set up at startup of the Host, and the Session is kept around by the >Host, even if there hasn't been anything which use that device all >day/week, etc. So I am not sure if having a certain amount of buffer space >reserved for each Host (which could be 100s-1000s) would be an especially >good idea. I believe we are in agreement both in terms of duration and the need to have dynamic buffer management. I will clarify that there will also be sessions that are not host focused, e.g. the peer-to-peer direction of a storage object to another device, e.g. multi-media streaming and these sessions will be shorter lived - possibly on a per transaction basis where a transaction is something of reasonably large in value (e.g. 100's MBs of data movement). Mike
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