Re: Reg: Bidirectional command format ?
"Eddy Quicksall" <[email protected]>
| Newsgroups | gmane.ietf.ips |
|---|---|
| Message-ID | <[email protected]> |
Is anyone aware of any bidi SCSI commands? Eddy ----- Original Message ----- From: "William Studenmund" <[email protected]> To: "Praveen Madhavan" <[email protected]> Cc: <[email protected]> Sent: Friday, June 16, 2006 3:04 PM Subject: Re: [Ips] Reg: Bidirectional command format ? > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Jun 16, 2006, at 5:37 AM, Praveen Madhavan wrote: > >> Hi Folks, >> >> Can any one point me the frame format of bidirectional command in >> case of iSCSI & FCP ?.. I was trying to route bidirectional command >> recv'd from iSCSI initiator to FC Target.. >> >> Here is the iSCSI PDU format for bi-direct command recv from initiator >> ---------------------------------------------------------------------- >> -------------------------- >> | BHS >> (48bytes) >> | >> | R & W bit set to >> ONE, | >> | Expected xfer len = >> 0x200 | >> | Total AHS Length = 2 >> (8bytes) | >> | SCSI CDB = Write(10) Transfer length = 00 01 ( 512 bytes) | >> >> ---------------------------------------------------------------------- >> --------------------------| >> | AHS ( 8 >> bytes) >> | >> | Expected Read data length = 0x200(512 >> bytes) | >> ---------------------------------------------------------------------- >> ---------------------------- >> >> Here is the FCP format for bi-direct command that i frame for >> sending it to target. >> >> ---------------------------------------------------------------------- >> -------------------------- >> | FC-Header >> (24bytes) | >> |--------------------------------------------------------------------- >> --------------------------- >> | FCP-Header(36 >> bytes) | >> | R & W bit set to >> ONE, | >> | Additional CDB length = >> 0 | >> | SCSI CDB = Write(10) Transfer length = 00 01 ( 512 >> bytes) | >> | FCP_DL = 0x200 ( 512 >> bytes) | >> | FCP_BIDIRECTIONAL_READ_DL = 0x200(512) | >> >> ---------------------------------------------------------------------- >> ---------------------------| >> >> Well, I am not quite sure about the CDB values in case Bidir >> commands.. >> Will Bi directional cmds use Write CDB(10) or Read CDB (10) ? .. > > No. Read and Write in normal sizes (6, 10, 12, 16) are unidirectional. > > Each specific command has either no data phase (test unit ready), has > at most a data-out phase (Write for instance), at most a data-in > phase (Read), or is bidirectional. > >> How can i control following bidi- operation in case of iSCSI & FCP ? >> 1.bidirectional command with read before write operation >> 2.bidirectional command with write before read operation > > You really don't need to do anything different for BiDi commands, > other than be able to keep both a Write and a Read residual. As you > note, the SCSI Command Request will indicate what data phases the > initiator expects, you need only map them along. > > How does the target announce/control data flow in FCP? You need only > pass that information on to the iSCSI layer. If the FCP target sends > you data, then you send the initiator a bunch of Data-In PDUs. > However it is that FCP controls data openings translates into R2Ts to > the iSCSI initiator. > > Take care, > > Bill > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.1 (Darwin) > > iD8DBQFEkwDZDJT2Egh26K0RAjqYAJ4yfTh+dkihI/Ha0RGhZN5NJ22zUQCfRc1L > 7fPzAAxZZUa3mX6JsaEMPYs= > =a55F > -----END PGP SIGNATURE----- > > _______________________________________________ > Ips mailing list > [email protected] > https://www1.ietf.org/mailman/listinfo/ips > _______________________________________________ Ips mailing list [email protected] https://www1.ietf.org/mailman/listinfo/ips